diff --git a/src/lexical/token.rs b/src/lexical/token.rs
index bc0f10b..0db18b8 100644
--- a/src/lexical/token.rs
+++ b/src/lexical/token.rs
@@ -52,6 +52,7 @@ pub enum KeywordKind {
     Int,
     Bool,
     Macro,
+    Val,
 }
 
 impl Display for KeywordKind {
@@ -117,6 +118,7 @@ impl KeywordKind {
             Self::Int => "int",
             Self::Bool => "bool",
             Self::Macro => "macro",
+            Self::Val => "val",
         }
     }
 
diff --git a/src/semantic/mod.rs b/src/semantic/mod.rs
index 2b97797..3642408 100644
--- a/src/semantic/mod.rs
+++ b/src/semantic/mod.rs
@@ -396,6 +396,10 @@ impl Assignment {
             let expected = match variable_type {
                 VariableType::BooleanStorage | VariableType::Tag => ValueType::Boolean,
                 VariableType::ScoreboardValue => ValueType::Integer,
+                VariableType::ComptimeValue => {
+                    // TODO: check if the expression is a constant expression
+                    return Ok(());
+                }
                 _ => {
                     let err = error::Error::AssignmentError(AssignmentError {
                         identifier: self.destination().span(),
@@ -445,6 +449,12 @@ impl VariableDeclaration {
                 KeywordKind::Int => (VariableType::ScoreboardValue, ExpectedType::Integer),
                 _ => unreachable!("variable type is not a valid type"),
             },
+            Self::ComptimeValue(decl) => {
+                if let Some(assignment) = decl.assignment() {
+                    assignment.expression().analyze_semantics(scope, handler)?;
+                }
+                (VariableType::ComptimeValue, ExpectedType::Any)
+            }
         };
         scope.set_variable(name, var);
         let assignment = match self {
@@ -459,7 +469,12 @@ impl VariableDeclaration {
                 }
             }
             Self::Single(single) => single.assignment().as_ref(),
+            Self::ComptimeValue(decl) => decl.assignment().as_ref(),
         };
+        if var == VariableType::ComptimeValue {
+            // TODO: check if the expression is a constant expression
+            return Ok(());
+        }
         if let Some(assignment) = assignment {
             let expected = match var {
                 VariableType::BooleanStorage | VariableType::Tag => ValueType::Boolean,
@@ -689,8 +704,35 @@ impl Binary {
         handler: &impl Handler<base::Error>,
     ) -> Result<(), error::Error> {
         match self.operator() {
-            BinaryOperator::Add(_)
-            | BinaryOperator::Subtract(_)
+            BinaryOperator::Add(_) => {
+                if (self
+                    .left_operand()
+                    .can_yield_type_semantics(ValueType::Integer, scope)
+                    && self
+                        .right_operand()
+                        .can_yield_type_semantics(ValueType::Integer, scope))
+                    || self
+                        .left_operand()
+                        .can_yield_type_semantics(ValueType::String, scope)
+                    || self
+                        .right_operand()
+                        .can_yield_type_semantics(ValueType::String, scope)
+                {
+                    self.left_operand().analyze_semantics(scope, handler)?;
+                    self.right_operand().analyze_semantics(scope, handler)
+                } else {
+                    let err = error::Error::MismatchedTypes(MismatchedTypes {
+                        expected_type: ExpectedType::AnyOf(vec![
+                            ExpectedType::Integer,
+                            ExpectedType::String,
+                        ]),
+                        expression: self.span(),
+                    });
+                    handler.receive(err.clone());
+                    Err(err)
+                }
+            }
+            BinaryOperator::Subtract(_)
             | BinaryOperator::Multiply(_)
             | BinaryOperator::Divide(_)
             | BinaryOperator::Modulo(_) => {
@@ -779,8 +821,8 @@ impl Binary {
 }
 
 impl LuaCode {
-    #[expect(clippy::unused_self, clippy::unnecessary_wraps)]
-    #[cfg_attr(feature = "lua", expect(unused_variables))]
+    #[expect(clippy::unused_self)]
+    #[cfg_attr(feature = "lua", expect(unused_variables, clippy::unnecessary_wraps))]
     fn analyze_semantics(
         &self,
         _scope: &SemanticScope,
diff --git a/src/semantic/scope.rs b/src/semantic/scope.rs
index ce1ce0f..6c9b4e3 100644
--- a/src/semantic/scope.rs
+++ b/src/semantic/scope.rs
@@ -21,6 +21,8 @@ pub enum VariableType {
     BooleanStorageArray,
     /// Compiler internal function.
     InternalFunction,
+    /// Compiler internal value.
+    ComptimeValue,
 }
 
 /// A scope that stores variables.
diff --git a/src/syntax/syntax_tree/statement.rs b/src/syntax/syntax_tree/statement.rs
index f457a75..eb567b1 100644
--- a/src/syntax/syntax_tree/statement.rs
+++ b/src/syntax/syntax_tree/statement.rs
@@ -325,6 +325,7 @@ pub enum VariableDeclaration {
     Array(ArrayVariableDeclaration),
     Score(ScoreVariableDeclaration),
     Tag(TagVariableDeclaration),
+    ComptimeValue(ComptimeValueDeclaration),
 }
 
 impl SourceElement for VariableDeclaration {
@@ -334,6 +335,7 @@ impl SourceElement for VariableDeclaration {
             Self::Array(declaration) => declaration.span(),
             Self::Score(declaration) => declaration.span(),
             Self::Tag(declaration) => declaration.span(),
+            Self::ComptimeValue(declaration) => declaration.span(),
         }
     }
 }
@@ -347,6 +349,7 @@ impl VariableDeclaration {
             Self::Array(declaration) => &declaration.identifier,
             Self::Score(declaration) => &declaration.identifier,
             Self::Tag(declaration) => &declaration.identifier,
+            Self::ComptimeValue(declaration) => &declaration.identifier,
         }
     }
 
@@ -358,6 +361,7 @@ impl VariableDeclaration {
             Self::Array(declaration) => &declaration.variable_type,
             Self::Score(declaration) => &declaration.int_keyword,
             Self::Tag(declaration) => &declaration.bool_keyword,
+            Self::ComptimeValue(declaration) => &declaration.val_keyword,
         }
     }
 
@@ -383,6 +387,14 @@ impl VariableDeclaration {
                 declaration.annotations.push_front(annotation);
                 Ok(Self::Tag(declaration))
             }
+            Self::ComptimeValue(_) => {
+                let err = Error::InvalidAnnotation(InvalidAnnotation {
+                    annotation: annotation.assignment.identifier.span,
+                    target: "comptime values".to_string(),
+                });
+
+                Err(err)
+            }
         }
     }
 }
@@ -681,6 +693,53 @@ impl TagVariableDeclaration {
     }
 }
 
+/// Represents a compile time value declaration in the syntax tree.
+///
+/// Syntax Synopsis:
+///
+/// ```ebnf
+/// ComptimeValueDeclaration:
+///     'val' identifier VariableDeclarationAssignment?
+/// ```
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+#[derive(Debug, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Getters)]
+pub struct ComptimeValueDeclaration {
+    /// The type of the variable.
+    #[get = "pub"]
+    val_keyword: Keyword,
+    /// The identifier of the variable.
+    #[get = "pub"]
+    identifier: Identifier,
+    /// The optional assignment of the variable.
+    #[get = "pub"]
+    assignment: Option<VariableDeclarationAssignment>,
+    /// The annotations of the variable declaration.
+    #[get = "pub"]
+    annotations: VecDeque<Annotation>,
+}
+
+impl SourceElement for ComptimeValueDeclaration {
+    fn span(&self) -> Span {
+        self.val_keyword
+            .span()
+            .join(
+                &self
+                    .assignment
+                    .as_ref()
+                    .map_or_else(|| self.identifier.span(), SourceElement::span),
+            )
+            .expect("The span of the single variable declaration is invalid.")
+    }
+}
+
+impl ComptimeValueDeclaration {
+    /// Dissolves the [`ComptimeValueDeclaration`] into its components.
+    #[must_use]
+    pub fn dissolve(self) -> (Keyword, Identifier, Option<VariableDeclarationAssignment>) {
+        (self.val_keyword, self.identifier, self.assignment)
+    }
+}
+
 /// Represents an assignment in the syntax tree.
 ///
 /// Syntax Synopsis:
@@ -883,7 +942,10 @@ impl Parser<'_> {
     ) -> ParseResult<Semicolon> {
         let statement = match self.stop_at_significant() {
             Reading::Atomic(Token::Keyword(keyword))
-                if matches!(keyword.keyword, KeywordKind::Int | KeywordKind::Bool) =>
+                if matches!(
+                    keyword.keyword,
+                    KeywordKind::Int | KeywordKind::Bool | KeywordKind::Val
+                ) =>
             {
                 self.parse_variable_declaration(handler)
                     .map(SemicolonStatement::VariableDeclaration)
@@ -895,18 +957,20 @@ impl Parser<'_> {
                     let destination = {
                         let identifier = p.parse_identifier(&VoidHandler)?;
 
-                        if let Ok(tree) = p.step_into(
-                            Delimiter::Bracket,
-                            |pp| pp.parse_expression(&VoidHandler),
-                            &VoidHandler,
-                        ) {
-                            let open = tree.open;
-                            let close = tree.close;
-                            let expression = tree.tree?;
+                        match p.stop_at_significant() {
+                            Reading::IntoDelimited(punc) if punc.punctuation == '[' => {
+                                let tree = p.step_into(
+                                    Delimiter::Bracket,
+                                    |pp| pp.parse_expression(&VoidHandler),
+                                    &VoidHandler,
+                                )?;
+                                let open = tree.open;
+                                let close = tree.close;
+                                let expression = tree.tree?;
 
-                            AssignmentDestination::Indexed(identifier, open, expression, close)
-                        } else {
-                            AssignmentDestination::Identifier(identifier)
+                                AssignmentDestination::Indexed(identifier, open, expression, close)
+                            }
+                            _ => AssignmentDestination::Identifier(identifier),
                         }
                     };
                     let equals = p.parse_punctuation('=', true, &VoidHandler)?;
@@ -948,7 +1012,10 @@ impl Parser<'_> {
 
         let variable_type = match self.stop_at_significant() {
             Reading::Atomic(Token::Keyword(keyword))
-                if matches!(keyword.keyword, KeywordKind::Int | KeywordKind::Bool) =>
+                if matches!(
+                    keyword.keyword,
+                    KeywordKind::Int | KeywordKind::Bool | KeywordKind::Val
+                ) =>
             {
                 self.forward();
                 keyword
@@ -983,7 +1050,10 @@ impl Parser<'_> {
         let identifier = self.parse_identifier(handler)?;
 
         match self.stop_at_significant() {
-            Reading::IntoDelimited(punc) if punc.punctuation == '[' => {
+            Reading::IntoDelimited(punc)
+                if punc.punctuation == '['
+                    && matches!(variable_type.keyword, KeywordKind::Int | KeywordKind::Bool) =>
+            {
                 let tree = self.step_into(
                     Delimiter::Bracket,
                     |p| {
@@ -1071,12 +1141,23 @@ impl Parser<'_> {
                 let expression = self.parse_expression(handler)?;
                 let assignment = VariableDeclarationAssignment { equals, expression };
 
-                Ok(VariableDeclaration::Single(SingleVariableDeclaration {
-                    variable_type,
-                    identifier,
-                    assignment: Some(assignment),
-                    annotations: VecDeque::new(),
-                }))
+                if variable_type.keyword == KeywordKind::Val {
+                    Ok(VariableDeclaration::ComptimeValue(
+                        ComptimeValueDeclaration {
+                            val_keyword: variable_type,
+                            identifier,
+                            assignment: Some(assignment),
+                            annotations: VecDeque::new(),
+                        },
+                    ))
+                } else {
+                    Ok(VariableDeclaration::Single(SingleVariableDeclaration {
+                        variable_type,
+                        identifier,
+                        assignment: Some(assignment),
+                        annotations: VecDeque::new(),
+                    }))
+                }
             }
             // SingleVariableDeclaration without Assignment
             _ => Ok(VariableDeclaration::Single(SingleVariableDeclaration {
diff --git a/src/transpile/error.rs b/src/transpile/error.rs
index 89d2ce5..fd9f834 100644
--- a/src/transpile/error.rs
+++ b/src/transpile/error.rs
@@ -46,6 +46,8 @@ pub enum TranspileError {
     IllegalIndexing(#[from] IllegalIndexing),
     #[error(transparent)]
     InvalidArgument(#[from] InvalidArgument),
+    #[error(transparent)]
+    NotComptime(#[from] NotComptime),
 }
 
 /// The result of a transpilation operation.
@@ -447,3 +449,32 @@ impl Display for InvalidArgument {
 }
 
 impl std::error::Error for InvalidArgument {}
+
+/// An error that occurs when an indexing operation is not permitted.
+#[derive(Debug, Clone, PartialEq, Eq, Getters)]
+pub struct NotComptime {
+    /// The expression that cannot be evaluated at compile time.
+    #[get = "pub"]
+    pub expression: Span,
+}
+
+impl Display for NotComptime {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{}",
+            Message::new(
+                Severity::Error,
+                "The expression cannot be evaluated at compile time but is required to."
+            )
+        )?;
+
+        write!(
+            f,
+            "\n{}",
+            SourceCodeDisplay::new(&self.expression, Option::<u8>::None)
+        )
+    }
+}
+
+impl std::error::Error for NotComptime {}
diff --git a/src/transpile/expression.rs b/src/transpile/expression.rs
index 72cdb7d..a0a0cf6 100644
--- a/src/transpile/expression.rs
+++ b/src/transpile/expression.rs
@@ -12,7 +12,9 @@ use shulkerbox::prelude::{Command, Condition, Execute};
 
 #[cfg(feature = "shulkerbox")]
 use super::{
-    error::{IllegalIndexing, IllegalIndexingReason, MismatchedTypes, UnknownIdentifier},
+    error::{
+        IllegalIndexing, IllegalIndexingReason, MismatchedTypes, NotComptime, UnknownIdentifier,
+    },
     Scope, TranspileResult, Transpiler, VariableData,
 };
 #[cfg(feature = "shulkerbox")]
@@ -238,12 +240,14 @@ impl Expression {
     }
 
     /// Evaluate at compile-time.
-    #[must_use]
+    ///
+    /// # Errors
+    /// - If the expression is not compile-time evaluatable.
     pub fn comptime_eval(
         &self,
         scope: &Arc<Scope>,
         handler: &impl Handler<base::Error>,
-    ) -> Option<ComptimeValue> {
+    ) -> Result<ComptimeValue, NotComptime> {
         match self {
             Self::Primary(primary) => primary.comptime_eval(scope, handler),
             Self::Binary(binary) => binary.comptime_eval(scope, handler),
@@ -333,19 +337,40 @@ impl Primary {
     }
 
     /// Evaluate at compile-time.
-    #[must_use]
+    ///
+    /// # Errors
+    /// - If the expression is not compile-time evaluatable.
     pub fn comptime_eval(
         &self,
         scope: &Arc<Scope>,
         handler: &impl Handler<base::Error>,
-    ) -> Option<ComptimeValue> {
+    ) -> Result<ComptimeValue, NotComptime> {
         match self {
-            Self::Boolean(boolean) => Some(ComptimeValue::Boolean(boolean.value())),
-            Self::Integer(int) => Some(ComptimeValue::Integer(int.as_i64())),
-            Self::StringLiteral(string_literal) => Some(ComptimeValue::String(
+            Self::Boolean(boolean) => Ok(ComptimeValue::Boolean(boolean.value())),
+            Self::Integer(int) => Ok(ComptimeValue::Integer(int.as_i64())),
+            Self::StringLiteral(string_literal) => Ok(ComptimeValue::String(
                 string_literal.str_content().to_string(),
             )),
-            Self::Identifier(_) | Self::FunctionCall(_) | Self::Indexed(_) => None,
+            Self::Identifier(ident) => scope.get_variable(ident.span.str()).map_or_else(
+                || {
+                    Err(NotComptime {
+                        expression: self.span(),
+                    })
+                },
+                |var| match var.as_ref() {
+                    VariableData::ComptimeValue { value } => {
+                        value.read().unwrap().clone().ok_or_else(|| NotComptime {
+                            expression: ident.span.clone(),
+                        })
+                    }
+                    _ => Err(NotComptime {
+                        expression: self.span(),
+                    }),
+                },
+            ),
+            Self::FunctionCall(_) | Self::Indexed(_) => Err(NotComptime {
+                expression: self.span(),
+            }),
             Self::Parenthesized(parenthesized) => {
                 parenthesized.expression().comptime_eval(scope, handler)
             }
@@ -355,12 +380,14 @@ impl Primary {
                     .comptime_eval(scope, handler)
                     .and_then(|val| match (prefix.operator(), val) {
                         (PrefixOperator::LogicalNot(_), ComptimeValue::Boolean(boolean)) => {
-                            Some(ComptimeValue::Boolean(!boolean))
+                            Ok(ComptimeValue::Boolean(!boolean))
                         }
                         (PrefixOperator::Negate(_), ComptimeValue::Integer(int)) => {
-                            Some(ComptimeValue::Integer(-int))
+                            Ok(ComptimeValue::Integer(-int))
                         }
-                        _ => None,
+                        _ => Err(NotComptime {
+                            expression: prefix.span(),
+                        }),
                     })
             }
             Self::Lua(lua) => lua
@@ -368,19 +395,21 @@ impl Primary {
                 .inspect_err(|err| {
                     handler.receive(err.clone());
                 })
-                .ok()
-                .flatten(),
+                .map_err(|_| NotComptime {
+                    expression: lua.span(),
+                })
+                .and_then(|val| val),
             Self::MacroStringLiteral(macro_string_literal) => {
                 if macro_string_literal
                     .parts()
                     .iter()
                     .any(|part| matches!(part, MacroStringLiteralPart::MacroUsage { .. }))
                 {
-                    Some(ComptimeValue::MacroString(
+                    Ok(ComptimeValue::MacroString(
                         macro_string_literal.clone().into(),
                     ))
                 } else {
-                    Some(ComptimeValue::String(macro_string_literal.str_content()))
+                    Ok(ComptimeValue::String(macro_string_literal.str_content()))
                 }
             }
         }
@@ -430,12 +459,14 @@ impl Binary {
     }
 
     /// Evaluate at compile-time.
-    #[must_use]
+    ///
+    /// # Errors
+    /// - If the expression is not compile-time evaluatable.
     pub fn comptime_eval(
         &self,
         scope: &Arc<Scope>,
         handler: &impl Handler<base::Error>,
-    ) -> Option<ComptimeValue> {
+    ) -> Result<ComptimeValue, NotComptime> {
         let left = self.left_operand().comptime_eval(scope, handler)?;
         let right = self.right_operand().comptime_eval(scope, handler)?;
 
@@ -449,7 +480,7 @@ impl Binary {
                         .right_operand()
                         .can_yield_type(ValueType::Boolean, scope) =>
             {
-                Some(ComptimeValue::Boolean(true))
+                Ok(ComptimeValue::Boolean(true))
             }
             (ComptimeValue::Boolean(false), _) | (_, ComptimeValue::Boolean(false))
                 if matches!(self.operator(), BinaryOperator::LogicalAnd(..))
@@ -460,15 +491,17 @@ impl Binary {
                         .right_operand()
                         .can_yield_type(ValueType::Boolean, scope) =>
             {
-                Some(ComptimeValue::Boolean(false))
+                Ok(ComptimeValue::Boolean(false))
             }
             (ComptimeValue::Boolean(left), ComptimeValue::Boolean(right)) => {
                 match self.operator() {
-                    BinaryOperator::Equal(..) => Some(ComptimeValue::Boolean(left == right)),
-                    BinaryOperator::NotEqual(..) => Some(ComptimeValue::Boolean(left != right)),
-                    BinaryOperator::LogicalAnd(..) => Some(ComptimeValue::Boolean(left && right)),
-                    BinaryOperator::LogicalOr(..) => Some(ComptimeValue::Boolean(left || right)),
-                    _ => None,
+                    BinaryOperator::Equal(..) => Ok(ComptimeValue::Boolean(left == right)),
+                    BinaryOperator::NotEqual(..) => Ok(ComptimeValue::Boolean(left != right)),
+                    BinaryOperator::LogicalAnd(..) => Ok(ComptimeValue::Boolean(left && right)),
+                    BinaryOperator::LogicalOr(..) => Ok(ComptimeValue::Boolean(left || right)),
+                    _ => Err(NotComptime {
+                        expression: self.span(),
+                    }),
                 }
             }
             (ComptimeValue::Integer(left), ComptimeValue::Integer(right)) => {
@@ -498,14 +531,37 @@ impl Binary {
                     }
                     _ => None,
                 }
+                .ok_or_else(|| NotComptime {
+                    expression: self.span(),
+                })
             }
             (ComptimeValue::String(left), ComptimeValue::String(right)) => match self.operator() {
-                BinaryOperator::Add(..) => Some(ComptimeValue::String(left + &right)),
-                BinaryOperator::Equal(..) => Some(ComptimeValue::Boolean(left == right)),
-                BinaryOperator::NotEqual(..) => Some(ComptimeValue::Boolean(left != right)),
-                _ => None,
+                BinaryOperator::Add(..) => Ok(ComptimeValue::String(left + &right)),
+                BinaryOperator::Equal(..) => Ok(ComptimeValue::Boolean(left == right)),
+                BinaryOperator::NotEqual(..) => Ok(ComptimeValue::Boolean(left != right)),
+                _ => Err(NotComptime {
+                    expression: self.span(),
+                }),
             },
-            _ => None,
+            // TODO: also allow macro strings
+            (
+                left @ ComptimeValue::String(_),
+                right @ (ComptimeValue::Boolean(_) | ComptimeValue::Integer(_)),
+            )
+            | (
+                left @ (ComptimeValue::Boolean(_) | ComptimeValue::Integer(_)),
+                right @ ComptimeValue::String(_),
+            ) => match self.operator() {
+                BinaryOperator::Add(_) => Ok(ComptimeValue::String(
+                    left.to_string_no_macro().unwrap() + &right.to_string_no_macro().unwrap(),
+                )),
+                _ => Err(NotComptime {
+                    expression: self.span(),
+                }),
+            },
+            _ => Err(NotComptime {
+                expression: self.span(),
+            }),
         }
     }
 }
@@ -641,7 +697,7 @@ impl Transpiler {
             Primary::Lua(lua) =>
             {
                 #[expect(clippy::option_if_let_else)]
-                if let Some(value) = lua.eval_comptime(scope, handler)? {
+                if let Ok(value) = lua.eval_comptime(scope, handler)? {
                     self.store_comptime_value(&value, target, lua, handler)
                 } else {
                     let err = TranspileError::MissingValue(MissingValue {
@@ -803,7 +859,7 @@ impl Transpiler {
                 if let Some(variable) = variable.as_deref() {
                     let from = match variable {
                         VariableData::Scoreboard { objective } => {
-                            if let Some(ComptimeValue::String(target)) =
+                            if let Ok(ComptimeValue::String(target)) =
                                 indexed.index().comptime_eval(scope, handler)
                             {
                                 Ok(DataLocation::ScoreboardValue {
@@ -822,7 +878,7 @@ impl Transpiler {
                             }
                         }
                         VariableData::ScoreboardArray { objective, targets } => {
-                            if let Some(ComptimeValue::Integer(index)) =
+                            if let Ok(ComptimeValue::Integer(index)) =
                                 indexed.index().comptime_eval(scope, handler)
                             {
                                 if let Some(target) = usize::try_from(index)
@@ -860,7 +916,7 @@ impl Transpiler {
                             storage_name,
                             paths,
                         } => {
-                            if let Some(ComptimeValue::Integer(index)) =
+                            if let Ok(ComptimeValue::Integer(index)) =
                                 indexed.index().comptime_eval(scope, handler)
                             {
                                 if let Some(path) = usize::try_from(index)
@@ -924,7 +980,7 @@ impl Transpiler {
         scope: &Arc<super::Scope>,
         handler: &impl Handler<base::Error>,
     ) -> TranspileResult<Vec<Command>> {
-        if let Some(value) = binary.comptime_eval(scope, handler) {
+        if let Ok(value) = binary.comptime_eval(scope, handler) {
             self.store_comptime_value(&value, target, binary, handler)
         } else {
             match binary.operator() {
@@ -1087,7 +1143,7 @@ impl Transpiler {
                             storage_name,
                             paths,
                         } => {
-                            if let Some(ComptimeValue::Integer(index)) =
+                            if let Ok(ComptimeValue::Integer(index)) =
                                 indexed.index().comptime_eval(scope, handler)
                             {
                                 if let Some(path) = usize::try_from(index)
@@ -1168,15 +1224,15 @@ impl Transpiler {
                 }
             },
             Primary::Lua(lua) => match lua.eval_comptime(scope, handler)? {
-                Some(ComptimeValue::String(value)) => Ok((
+                Ok(ComptimeValue::String(value)) => Ok((
                     Vec::new(),
                     ExtendedCondition::Runtime(Condition::Atom(value.into())),
                 )),
-                Some(ComptimeValue::MacroString(value)) => Ok((
+                Ok(ComptimeValue::MacroString(value)) => Ok((
                     Vec::new(),
                     ExtendedCondition::Runtime(Condition::Atom(value.into())),
                 )),
-                Some(ComptimeValue::Boolean(boolean)) => {
+                Ok(ComptimeValue::Boolean(boolean)) => {
                     Ok((Vec::new(), ExtendedCondition::Comptime(boolean)))
                 }
                 _ => {
diff --git a/src/transpile/function.rs b/src/transpile/function.rs
index fde399a..e2eb30e 100644
--- a/src/transpile/function.rs
+++ b/src/transpile/function.rs
@@ -102,6 +102,7 @@ impl Transpiler {
                     TranspileAnnotationValue::None => Ok(identifier_span.str().to_string()),
                     TranspileAnnotationValue::Expression(expr) => expr
                         .comptime_eval(scope, handler)
+                        .ok()
                         .and_then(|val| val.to_string_no_macro())
                         .ok_or_else(|| {
                             let err = TranspileError::IllegalAnnotationContent(
@@ -293,13 +294,10 @@ impl Transpiler {
                     let value = match expression {
                         Expression::Primary(Primary::Lua(lua)) => {
                             lua.eval_comptime(scope, handler).and_then(|val| match val {
-                                Some(ComptimeValue::MacroString(s)) => Ok(Parameter::Static(s)),
-                                Some(val) => Ok(Parameter::Static(val.to_macro_string())),
-                                None => {
-                                    let err = TranspileError::MismatchedTypes(MismatchedTypes {
-                                        expression: expression.span(),
-                                        expected_type: ExpectedType::String,
-                                    });
+                                Ok(ComptimeValue::MacroString(s)) => Ok(Parameter::Static(s)),
+                                Ok(val) => Ok(Parameter::Static(val.to_macro_string())),
+                                Err(err) => {
+                                    let err = TranspileError::NotComptime(err);
                                     handler.receive(err.clone());
                                     Err(err)
                                 }
diff --git a/src/transpile/internal_functions.rs b/src/transpile/internal_functions.rs
index ebd9a96..fb0dfad 100644
--- a/src/transpile/internal_functions.rs
+++ b/src/transpile/internal_functions.rs
@@ -183,17 +183,17 @@ fn print_function(
 
     let args = get_args_assert_in_range(call, 1..=2)?;
     let first = args.first().expect("checked range");
-    let (target, message_expression) = args.get(1).map_or_else(
-        || ("@a".into(), first),
-        |second| {
-            (
-                first
-                    .comptime_eval(scope, &VoidHandler)
-                    .map_or_else(|| "@a".into(), |val| val.to_macro_string()),
-                second,
-            )
-        },
-    );
+    let (target, message_expression) = if let Some(second) = args.get(1) {
+        (
+            first
+                .comptime_eval(scope, &VoidHandler)
+                .map(|val| val.to_macro_string())
+                .map_err(TranspileError::NotComptime)?,
+            second,
+        )
+    } else {
+        ("@a".into(), first)
+    };
 
     let mut contains_macro = matches!(target, MacroString::MacroString(_));
 
@@ -240,7 +240,7 @@ fn print_function(
                 Primary::Identifier(ident) => {
                     match scope.get_variable(ident.span.str()).as_deref() {
                         Some(VariableData::Scoreboard { objective }) => {
-                            if let Some(ComptimeValue::String(index)) =
+                            if let Ok(ComptimeValue::String(index)) =
                                 indexed.index().comptime_eval(scope, &VoidHandler)
                             {
                                 let (cmd, value) = get_data_location(
@@ -262,7 +262,7 @@ fn print_function(
                             }
                         }
                         Some(VariableData::ScoreboardArray { objective, targets }) => {
-                            if let Some(ComptimeValue::Integer(index)) =
+                            if let Ok(ComptimeValue::Integer(index)) =
                                 indexed.index().comptime_eval(scope, &VoidHandler)
                             {
                                 #[expect(clippy::option_if_let_else)]
@@ -300,7 +300,7 @@ fn print_function(
                             storage_name,
                             paths,
                         }) => {
-                            if let Some(ComptimeValue::Integer(index)) =
+                            if let Ok(ComptimeValue::Integer(index)) =
                                 indexed.index().comptime_eval(scope, &VoidHandler)
                             {
                                 #[expect(clippy::option_if_let_else)]
diff --git a/src/transpile/lua.rs b/src/transpile/lua.rs
index bc792d0..27fa353 100644
--- a/src/transpile/lua.rs
+++ b/src/transpile/lua.rs
@@ -12,8 +12,8 @@ mod enabled {
         syntax::syntax_tree::expression::LuaCode,
         transpile::{
             error::{
-                InvalidArgument, LuaRuntimeError, MismatchedTypes, TranspileError, TranspileResult,
-                UnknownIdentifier,
+                InvalidArgument, LuaRuntimeError, MismatchedTypes, NotComptime, TranspileError,
+                TranspileResult, UnknownIdentifier,
             },
             expression::{ComptimeValue, ExpectedType},
             Scope, VariableData,
@@ -86,11 +86,15 @@ mod enabled {
             &self,
             scope: &Arc<Scope>,
             handler: &impl Handler<base::Error>,
-        ) -> TranspileResult<Option<ComptimeValue>> {
+        ) -> TranspileResult<Result<ComptimeValue, NotComptime>> {
             // required to keep the lua instance alive
             let (lua_result, _lua) = self.eval(scope, handler)?;
 
-            self.handle_lua_result(lua_result, handler)
+            self.handle_lua_result(lua_result, handler).map(|res| {
+                res.ok_or_else(|| NotComptime {
+                    expression: self.span(),
+                })
+            })
         }
 
         fn add_globals(&self, lua: &Lua, scope: &Arc<Scope>) -> TranspileResult<()> {
@@ -262,6 +266,22 @@ mod enabled {
                         .map_err(|err| LuaRuntimeError::from_lua_err(&err, self.span()))?;
                     Value::Table(table)
                 }
+                Some(VariableData::ComptimeValue { value }) => {
+                    let value = value.read().unwrap();
+                    match &*value {
+                        Some(ComptimeValue::Boolean(b)) => Value::Boolean(*b),
+                        Some(ComptimeValue::Integer(i)) => Value::Integer(*i),
+                        Some(ComptimeValue::String(s)) => Value::String(
+                            lua.create_string(s)
+                                .map_err(|err| LuaRuntimeError::from_lua_err(&err, self.span()))?,
+                        ),
+                        Some(ComptimeValue::MacroString(s)) => Value::String(
+                            lua.create_string(s.to_string())
+                                .map_err(|err| LuaRuntimeError::from_lua_err(&err, self.span()))?,
+                        ),
+                        None => Value::Nil,
+                    }
+                }
                 Some(VariableData::Function { .. } | VariableData::InternalFunction { .. }) => {
                     // TODO: add support for functions
                     return Err(TranspileError::InvalidArgument(InvalidArgument {
diff --git a/src/transpile/transpiler.rs b/src/transpile/transpiler.rs
index 69c95af..edac539 100644
--- a/src/transpile/transpiler.rs
+++ b/src/transpile/transpiler.rs
@@ -25,7 +25,7 @@ use crate::{
 };
 
 use super::{
-    error::{MismatchedTypes, TranspileError, TranspileResult},
+    error::{MismatchedTypes, MissingValue, TranspileError, TranspileResult, UnknownIdentifier},
     expression::{ComptimeValue, ExpectedType, ExtendedCondition},
     variables::{Scope, TranspileAssignmentTarget, VariableData},
     FunctionData, TranspileAnnotationValue, TranspiledFunctionArguments,
@@ -342,11 +342,46 @@ impl Transpiler {
             Expression::Primary(Primary::FunctionCall(func)) => {
                 self.transpile_function_call(func, scope, handler)
             }
+            Expression::Primary(Primary::Identifier(ident)) => {
+                match scope.get_variable(ident.span.str()).as_deref() {
+                    Some(VariableData::ComptimeValue { value }) => {
+                        value.read().unwrap().as_ref().map_or_else(
+                            || {
+                                let error = TranspileError::MissingValue(MissingValue {
+                                    expression: ident.span.clone(),
+                                });
+                                handler.receive(error.clone());
+                                Err(error)
+                            },
+                            |val| {
+                                let cmd = val.to_string_no_macro().map_or_else(
+                                    || Command::UsesMacro(val.to_macro_string().into()),
+                                    Command::Raw,
+                                );
+                                Ok(vec![cmd])
+                            },
+                        )
+                    }
+                    Some(_) => {
+                        let error = TranspileError::UnexpectedExpression(UnexpectedExpression(
+                            expression.clone(),
+                        ));
+                        handler.receive(error.clone());
+                        Err(error)
+                    }
+                    None => {
+                        let error = TranspileError::UnknownIdentifier(UnknownIdentifier {
+                            identifier: ident.span.clone(),
+                        });
+                        handler.receive(error.clone());
+                        Err(error)
+                    }
+                }
+            }
             expression @ Expression::Primary(
                 Primary::Integer(_)
                 | Primary::Boolean(_)
                 | Primary::Prefix(_)
-                | Primary::Identifier(_)
                 | Primary::Indexed(_),
             ) => {
                 let error =
@@ -361,9 +396,9 @@ impl Transpiler {
                 Ok(vec![Command::UsesMacro(string.into())])
             }
             Expression::Primary(Primary::Lua(code)) => match code.eval_comptime(scope, handler)? {
-                Some(ComptimeValue::String(cmd)) => Ok(vec![Command::Raw(cmd)]),
-                Some(ComptimeValue::MacroString(cmd)) => Ok(vec![Command::UsesMacro(cmd.into())]),
-                Some(ComptimeValue::Boolean(_) | ComptimeValue::Integer(_)) => {
+                Ok(ComptimeValue::String(cmd)) => Ok(vec![Command::Raw(cmd)]),
+                Ok(ComptimeValue::MacroString(cmd)) => Ok(vec![Command::UsesMacro(cmd.into())]),
+                Ok(ComptimeValue::Boolean(_) | ComptimeValue::Integer(_)) => {
                     let err = TranspileError::MismatchedTypes(MismatchedTypes {
                         expected_type: ExpectedType::String,
                         expression: code.span(),
@@ -371,7 +406,13 @@ impl Transpiler {
                     handler.receive(err.clone());
                     Err(err)
                 }
-                None => Ok(Vec::new()),
+                Err(_) => {
+                    let err = TranspileError::MissingValue(MissingValue {
+                        expression: code.span(),
+                    });
+                    handler.receive(err.clone());
+                    Err(err)
+                }
             },
 
             Expression::Primary(Primary::Parenthesized(parenthesized)) => self
@@ -382,8 +423,8 @@ impl Transpiler {
                     handler,
                 ),
             Expression::Binary(bin) => match bin.comptime_eval(scope, handler) {
-                Some(ComptimeValue::String(cmd)) => Ok(vec![Command::Raw(cmd)]),
-                Some(ComptimeValue::MacroString(cmd)) => Ok(vec![Command::UsesMacro(cmd.into())]),
+                Ok(ComptimeValue::String(cmd)) => Ok(vec![Command::Raw(cmd)]),
+                Ok(ComptimeValue::MacroString(cmd)) => Ok(vec![Command::UsesMacro(cmd.into())]),
                 _ => {
                     let err = TranspileError::MismatchedTypes(MismatchedTypes {
                         expression: bin.span(),
@@ -621,7 +662,7 @@ impl Transpiler {
             }
         });
 
-        if let Some(ComptimeValue::Boolean(value)) = cond_expression.comptime_eval(scope, handler) {
+        if let Ok(ComptimeValue::Boolean(value)) = cond_expression.comptime_eval(scope, handler) {
             if value {
                 Ok(Some((Vec::new(), then)))
             } else {
diff --git a/src/transpile/variables.rs b/src/transpile/variables.rs
index dd88872..a256a74 100644
--- a/src/transpile/variables.rs
+++ b/src/transpile/variables.rs
@@ -30,7 +30,7 @@ use crate::{
 use super::{
     error::{
         AssignmentError, IllegalAnnotationContent, IllegalIndexing, IllegalIndexingReason,
-        MismatchedTypes,
+        MismatchedTypes, NotComptime,
     },
     expression::{ComptimeValue, DataLocation, ExpectedType, StorageType},
     FunctionData, TranspileAnnotationValue, TranspileError, TranspileResult,
@@ -100,6 +100,11 @@ pub enum VariableData {
         /// The implementation
         implementation: InternalFunction,
     },
+    /// Compiler internal variable.
+    ComptimeValue {
+        /// The value.
+        value: Arc<RwLock<Option<ComptimeValue>>>,
+    },
 }
 
 #[derive(Debug, Clone, Copy, EnumAsInner)]
@@ -282,6 +287,31 @@ impl Transpiler {
                 scope,
                 handler,
             ),
+            VariableDeclaration::ComptimeValue(declaration) => {
+                let value = if let Some(assignment) = declaration.assignment() {
+                    Some(
+                        assignment
+                            .expression()
+                            .comptime_eval(scope, handler)
+                            .map_err(|err| {
+                                let err = TranspileError::NotComptime(err);
+                                handler.receive(err.clone());
+                                err
+                            })?,
+                    )
+                } else {
+                    None
+                };
+
+                scope.set_variable(
+                    declaration.identifier().span.str(),
+                    VariableData::ComptimeValue {
+                        value: Arc::new(RwLock::new(value)),
+                    },
+                );
+
+                Ok(Vec::new())
+            }
         }
     }
 
@@ -466,7 +496,7 @@ impl Transpiler {
         let (identifier, indexing_value) = match destination {
             TranspileAssignmentTarget::Identifier(ident) => (ident, None),
             TranspileAssignmentTarget::Indexed(ident, expression) => {
-                (ident, expression.comptime_eval(scope, handler))
+                (ident, expression.comptime_eval(scope, handler).ok())
             }
         };
         if let Some(target) = scope.get_variable(identifier.span.str()) {
@@ -662,6 +692,16 @@ impl Transpiler {
                         return Err(err);
                     }
                 },
+                VariableData::ComptimeValue { value } => {
+                    let comptime_value =
+                        expression.comptime_eval(scope, handler).map_err(|err| {
+                            let err = TranspileError::NotComptime(err);
+                            handler.receive(err.clone());
+                            err
+                        })?;
+                    *value.write().unwrap() = Some(comptime_value);
+                    return Ok(Vec::new());
+                }
                 VariableData::Function { .. }
                 | VariableData::MacroParameter { .. }
                 | VariableData::InternalFunction { .. } => {
@@ -723,6 +763,7 @@ impl Transpiler {
                 TranspileAnnotationValue::Expression(expr) => {
                     if let Some(name_eval) = expr
                         .comptime_eval(scope, handler)
+                        .ok()
                         .and_then(|val| val.to_string_no_macro())
                     {
                         // TODO: change invalid criteria if boolean
@@ -821,9 +862,11 @@ impl Transpiler {
                         if let (Some(name_eval), Some(target_eval)) = (
                             objective
                                 .comptime_eval(scope, handler)
+                                .ok()
                                 .and_then(|val| val.to_string_no_macro()),
                             target
                                 .comptime_eval(scope, handler)
+                                .ok()
                                 .and_then(|val| val.to_string_no_macro()),
                         ) {
                             // TODO: change invalid criteria if boolean