diff --git a/HILFE.Tests/Framework/Reflection/TypenameFunctionTest.cs b/HILFE.Tests/Framework/Reflection/TypenameFunctionTest.cs
new file mode 100644
index 00000000..f8bdd6b9
--- /dev/null
+++ b/HILFE.Tests/Framework/Reflection/TypenameFunctionTest.cs
@@ -0,0 +1,56 @@
+using HILFE.Framework.Reflection;
+using HILFE.Interpreting;
+using HILFE.Parsing.Expressions;
+using HILFE.Tokenizing;
+
+namespace HILFE.Tests.Framework.Reflection;
+
+public class TypenameFunctionTest
+{
+    [Theory]
+    [ClassData(typeof(TypenameData))]
+    public async Task TestEvaluateAsync(string typeName, ExpressionResult arg)
+    {
+        const string varName = "a";
+        var interpreter = new Interpreter();
+        interpreter.CurrentScope.SetVariable(varName, arg);
+        
+        var function = new TypenameFunction();
+        var result = await function.EvaluateAsync(interpreter, new []{ new VariableExpression(new(TokenType.Identifier, varName)) });
+
+        Assert.Equal("string", result.ValueType);
+        Assert.Equal(typeName, result.Value as string);
+    }
+
+    [Fact]
+    public async Task TestEvaluateAsyncThrowsForNonVariableExpression()
+    {
+        var interpreter = new Interpreter();
+        var function = new TypenameFunction();
+        
+        await Assert.ThrowsAsync<InvalidExpressionTypeException>(() => function.EvaluateAsync(interpreter, new []{ ConstantExpression.String("abc") }));
+    }
+
+    [Fact]
+    public async Task TestEvaluateAsyncThrowsForInvalidArgCounts()
+    {
+        var interpreter = new Interpreter();
+        var function = new TypenameFunction();
+        
+        await Assert.ThrowsAsync<InvalidArgumentCountException>(() => function.EvaluateAsync(interpreter, new []{ ConstantExpression.String("abc"), ConstantExpression.String("abc") }));
+        await Assert.ThrowsAsync<InvalidArgumentCountException>(() => function.EvaluateAsync(interpreter, Array.Empty<Expression>()));
+    }
+
+    private class TypenameData : TheoryData<string, ExpressionResult>
+    {
+        public TypenameData()
+        {
+            Add("null", ExpressionResult.Null);
+            Add("void", ExpressionResult.Void);
+            Add("bool", ExpressionResult.True);
+            Add("number", ExpressionResult.Number(123));
+            Add("string", ExpressionResult.String("test"));
+            Add("function", ExpressionResult.Function(new TypenameFunction()));
+        }
+    }
+}
\ No newline at end of file
diff --git a/HILFE/Parsing/Expressions/ExpressionResult.cs b/HILFE/Parsing/Expressions/ExpressionResult.cs
index 65eb6103..fdb5dc40 100644
--- a/HILFE/Parsing/Expressions/ExpressionResult.cs
+++ b/HILFE/Parsing/Expressions/ExpressionResult.cs
@@ -11,6 +11,14 @@ public record ExpressionResult(string ValueType, dynamic? Value = null, bool IsV
     public static ExpressionResult True { get; } = new("bool", true);
 
     public static ExpressionResult False { get; } = new("bool", false);
+    
+    public static ExpressionResult Number(double value) => new("number", value);
+    
+    public static ExpressionResult String(string value) => new("string", value);
+
+    public static ExpressionResult Bool(bool value) => new("bool", value);
+
+    public static ExpressionResult Function(FunctionDefinition definition) => new("function", definition);
 
     /// <inheritdoc />
     public virtual bool Equals(ExpressionResult? other)