diff --git a/CHANGELOG.md b/CHANGELOG.md
index ef5456acf..0d4b26a50 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -33,7 +33,7 @@ To use development versions of Kipper download the
 - Implemented internal generic spread argument `T...`, which allows multiple arguments to be passed to a single
   parameter inside of a generic type specifier.
 - Implemented constant `NaN`, which represents the `NaN` value in JavaScript (Not a Number).
-	([#671](https://github.com/Kipper-Lang/Kipper/issues/671))
+  ([#671](https://github.com/Kipper-Lang/Kipper/issues/671))
 - New module:
   - `semantics/runtime-built-ins`, which contains runtime built-in functions, variables and types.
   - `semantics/runtime-internals`, which contains the runtime internal functions.
diff --git a/kipper/core/KipperLexer.g4 b/kipper/core/KipperLexer.g4
index b915d40ec..512ba06a8 100644
--- a/kipper/core/KipperLexer.g4
+++ b/kipper/core/KipperLexer.g4
@@ -88,7 +88,6 @@ False : 'false';
 
 // typeof operator
 Typeof : 'typeof';
-DefFunc : 'def';
 
 // Constant undefined, void and null identifiers
 Void : 'void';
diff --git a/kipper/core/src/compiler/ast/nodes/expressions/type-specifier-expression/typeof-type-specifier-expression/typeof-type-specifier-expression-semantics.ts b/kipper/core/src/compiler/ast/nodes/expressions/type-specifier-expression/typeof-type-specifier-expression/typeof-type-specifier-expression-semantics.ts
index b2978826a..9ffece27a 100644
--- a/kipper/core/src/compiler/ast/nodes/expressions/type-specifier-expression/typeof-type-specifier-expression/typeof-type-specifier-expression-semantics.ts
+++ b/kipper/core/src/compiler/ast/nodes/expressions/type-specifier-expression/typeof-type-specifier-expression/typeof-type-specifier-expression-semantics.ts
@@ -3,7 +3,7 @@
  * @since 0.8.0
  */
 import type { TypeSpecifierExpressionSemantics } from "../type-specifier-expression-semantics";
-import type { Expression } from "../../expression";
+import type { ProcessedType } from "../../../../../semantics";
 
 /**
  * Semantics for AST Node {@link TypeofTypeSpecifierExpression}.
@@ -11,8 +11,8 @@ import type { Expression } from "../../expression";
  */
 export interface TypeofTypeSpecifierExpressionSemantics extends TypeSpecifierExpressionSemantics {
 	/**
-	 * The expression to evaluate the type of.
-	 * @since 0.8.0
+	 * The checked type for this typeof expression.
+	 * @since 0.12.0
 	 */
-	object: Expression;
+	evaluatedType: ProcessedType;
 }
diff --git a/kipper/core/src/compiler/ast/nodes/expressions/type-specifier-expression/typeof-type-specifier-expression/typeof-type-specifier-expression.ts b/kipper/core/src/compiler/ast/nodes/expressions/type-specifier-expression/typeof-type-specifier-expression/typeof-type-specifier-expression.ts
index b43bf7419..a95787d23 100644
--- a/kipper/core/src/compiler/ast/nodes/expressions/type-specifier-expression/typeof-type-specifier-expression/typeof-type-specifier-expression.ts
+++ b/kipper/core/src/compiler/ast/nodes/expressions/type-specifier-expression/typeof-type-specifier-expression/typeof-type-specifier-expression.ts
@@ -8,7 +8,7 @@ import type { CompilableASTNode } from "../../../../compilable-ast-node";
 import { TypeSpecifierExpression } from "../type-specifier-expression";
 import type { TypeofTypeSpecifierExpressionContext } from "../../../../../lexer-parser";
 import { KindParseRuleMapping, ParseRuleKindMapping } from "../../../../../lexer-parser";
-import { KipperNotImplementedError } from "../../../../../../errors";
+import { RawType } from "../../../../../semantics";
 
 /**
  * Typeof type specifier expression, which represents a runtime typeof expression evaluating the type of a value.
@@ -81,13 +81,13 @@ export class TypeofTypeSpecifierExpression extends TypeSpecifierExpression<
 	 * the children has already failed and as such no parent node should run type checking.
 	 */
 	public async primarySemanticAnalysis(): Promise<void> {
-		const objectToValidate = this.children[0];
+		const expression = this.children[0];
 
 		this.programCtx.semanticCheck(this);
 
 		this.semanticData = {
-			object: objectToValidate,
-			rawType: objectToValidate.getTypeSemanticData().evaluatedType,
+			evaluatedType: expression.getTypeSemanticData().evaluatedType,
+			rawType: new RawType(expression.sourceCode)
 		};
 	}
 
@@ -102,7 +102,7 @@ export class TypeofTypeSpecifierExpression extends TypeSpecifierExpression<
 		this.programCtx.semanticCheck(this);
 
 		this.typeSemantics = {
-			storedType: semanticData.object.getTypeSemanticData().evaluatedType,
+			storedType: semanticData.object.g,
 			evaluatedType: semanticData.object.getTypeSemanticData().evaluatedType,
 		};
 	}
diff --git a/test/kipper-files/typeof.kip b/test/kipper-files/typeof.kip
index eec157018..aff666fe5 100644
--- a/test/kipper-files/typeof.kip
+++ b/test/kipper-files/typeof.kip
@@ -1,9 +1,6 @@
 interface X {
-  a: str;
-  b: num;
-}
-
-var y: X = {
-	a: "hello",
-	b: 5
+	a: num;
+	b: str;
 };
+
+var x: typeof(null);