diff --git a/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java b/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
index 4ba5b6f..825a5bc 100644
--- a/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
+++ b/src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java
@@ -774,69 +774,72 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
 
   @Override
   public Node visitFunctionDef(KlangParser.FunctionDefContext ctx) {
-    String name = ctx.funcName.getText();
-    int line = ctx.start.getLine();
-    int col = ctx.start.getCharPositionInLine();
-    Type returnType = Type.getByName(ctx.returnType.type().getText());
-    this.currentDeclaredReturnType = returnType;
-    this.currentFunctionDefinitionName = name;
+    var name = ctx.funcName.getText();
+    var returnType = Type.getByName(ctx.returnType.type().getText());
+    currentDeclaredReturnType = returnType;
+    currentFunctionDefinitionName = name;
 
-    if (!returnType.isPrimitiveType() && this.structDefs.get(returnType.getName()) == null) {
-      String error = "Type " + returnType.getName() + " not defined.";
+    if (!returnType.isPrimitiveType() && !structDefs.containsKey(returnType.getName()) && !enumDefs.containsKey(returnType.getName())) {
+      var line = ctx.returnType.start.getLine();
+      var col = ctx.returnType.start.getCharPositionInLine();
+      var error = "Type " + returnType.getName() + " not defined.";
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
     // Create a new set for the variables of the current function
-    // this will be filled in the variable declaration visitor aswell
-    this.vars = new HashMap<>();
+    // this will be filled in the variable declaration visitor as well
+    vars = new HashMap<>();
 
-    // Process the paremter list by visiting every paremter in it
-    int paramCount = ctx.params.parameter().size();
-    Parameter[] params = new Parameter[paramCount];
+    // Process the parameter list by visiting every parameter in it
+    var paramCount = ctx.params.parameter().size();
+    var params = new Parameter[paramCount];
     for (int i = 0; i < paramCount; i++) {
       // Add the parameter to the list of parameters
-      Parameter param = (Parameter) this.visit(ctx.params.parameter(i));
+      var param = (Parameter) visit(ctx.params.parameter(i));
       params[i] = param;
 
       // add the param as a variable
-      VariableDeclaration var = new VariableDeclaration(param.name);
+      var var = new VariableDeclaration(param.name);
       var.initialized = true; // parameters can always be considered initialized
       var.type = param.type;
-      this.vars.put(param.name, var);
+      vars.put(param.name, var);
     }
 
     // Visit the block, make sure that a return value is guaranteed
-    Node block = this.visit(ctx.braced_block());
+    var block = visit(ctx.braced_block());
     if (block.type == null) {
-      String error = "Function " + name + " has to return something of type " + returnType.getName() + ".";
+      var line = ctx.braced_block().start.getLine();
+      var col = ctx.braced_block().start.getCharPositionInLine();
+      var error = "Function " + name + " has to return something of type " + returnType.getName() + ".";
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
-    FunctionDefinition result = new FunctionDefinition(name, params, (Block) block);
-    result.type = returnType;
+    var functionDef = new FunctionDefinition(name, params, (Block) block);
+    functionDef.type = returnType;
+    functionDef.line = ctx.start.getLine();
+    functionDef.col = ctx.start.getCharPositionInLine();
 
-    result.line = ctx.start.getLine();
-    result.col = ctx.start.getCharPositionInLine();
-    return result;
+    return functionDef;
   }
 
   @Override
   public Node visitParameter(KlangParser.ParameterContext ctx) {
-    String name = ctx.IDENT().getText();
-    int line = ctx.start.getLine();
-    int col = ctx.start.getCharPositionInLine();
-    Type type = Type.getByName(ctx.type_annotation().type().getText());
+    var parameterName = ctx.IDENT().getText();
+    var parameterType = Type.getByName(ctx.type_annotation().type().getText());
 
-    if (!type.isPrimitiveType() && this.structDefs.get(type.getName()) == null) {
-      String error = "Type " + type.getName() + " not defined.";
+    if (!parameterType.isPrimitiveType() && !structDefs.containsKey(parameterType.getName()) && !enumDefs.containsKey(parameterType.getName())) {
+      var line = ctx.type_annotation().start.getLine();
+      var col = ctx.type_annotation().start.getCharPositionInLine();
+      String error = "Type " + parameterType.getName() + " not defined.";
       throw new RuntimeException(Helper.getErrorPrefix(line, col) + error);
     }
 
-    Parameter result = new Parameter(name);
-    result.type = type;
-    result.line = line;
-    result.col = col;
-    return result;
+    var parameter = new Parameter(parameterName);
+    parameter.type = parameterType;
+    parameter.line = ctx.start.getLine();
+    parameter.col = ctx.start.getCharPositionInLine();
+
+    return parameter;
   }
 
   @Override
diff --git a/src/test/java/FunctionDefinitionTest.java b/src/test/java/FunctionDefinitionTest.java
index 665b6e9..0d79c6a 100644
--- a/src/test/java/FunctionDefinitionTest.java
+++ b/src/test/java/FunctionDefinitionTest.java
@@ -1,34 +1,82 @@
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
-
 import org.antlr.v4.runtime.tree.ParseTree;
 import org.junit.jupiter.api.Test;
 
 import de.hsrm.compiler.Klang.ContextAnalysis;
 
+import static org.junit.jupiter.api.Assertions.*;
+
 public class FunctionDefinitionTest {
 
     @Test
-    void typeNotDefined() {
-        ParseTree tree = Helper.prepareParser("function foo(): schwurbel { return 1; } foo();");
-        var funcs = Helper.getFuncs(tree);
-        var structs = Helper.getStructs(tree);
-        var enums = Helper.getEnums(tree);
-        ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
-        
-        Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:0 Type schwurbel not defined.", e.getMessage());
+    void shouldNotThrowIfReturnTypeIsReferringToAnEnum() {
+        // given
+        var tree = Helper.prepareParser(" enum bar {A,B,C} function foo(a: int): bar { return bar.A; } foo();");
+        var ctxAnal = new ContextAnalysis(
+                Helper.getFuncs(tree),
+                Helper.getStructs(tree),
+                Helper.getEnums(tree)
+        );
+
+        // when / then
+        assertDoesNotThrow(() -> ctxAnal.visit(tree));
     }
 
     @Test
-    void noReturnExpression() {
-        ParseTree tree = Helper.prepareParser("function foo(): int { let x: int; x = 0; } foo();");
-        var funcs = Helper.getFuncs(tree);
-        var structs = Helper.getStructs(tree);
-        var enums = Helper.getEnums(tree);
-        ContextAnalysis ctxAnal = new ContextAnalysis(funcs, structs, enums);
-        
-        Exception e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
-        assertEquals("Error in line 1:0 Function foo has to return something of type int.", e.getMessage());
+    void shouldNotThrowIfParameterTypeIsReferringToAnEnum() {
+        // given
+        var tree = Helper.prepareParser(" enum bar {A,B,C} function foo(a: bar): int { return 1; } foo(bar.A);");
+        var ctxAnal = new ContextAnalysis(
+                Helper.getFuncs(tree),
+                Helper.getStructs(tree),
+                Helper.getEnums(tree)
+        );
+
+        // when / then
+        assertDoesNotThrow(() -> ctxAnal.visit(tree));
+    }
+
+    @Test
+    void shouldThrowExceptionIfParameterTypeIsNotDefined() {
+        // given
+        var tree = Helper.prepareParser("function foo(a: schwurbel): int { return 1; } foo();");
+        var ctxAnal = new ContextAnalysis(
+                Helper.getFuncs(tree),
+                Helper.getStructs(tree),
+                Helper.getEnums(tree)
+        );
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
+        assertEquals("Error in line 1:14 Type schwurbel not defined.", e.getMessage());
+    }
+
+    @Test
+    void shouldThrowExceptionIfReturnTypeIsNotDefined() {
+        // given
+        var tree = Helper.prepareParser("function foo(): schwurbel { return 1; } foo();");
+        var ctxAnal = new ContextAnalysis(
+                Helper.getFuncs(tree),
+                Helper.getStructs(tree),
+                Helper.getEnums(tree)
+        );
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
+        assertEquals("Error in line 1:14 Type schwurbel not defined.", e.getMessage());
+    }
+
+    @Test
+    void shouldThrowExceptionIfReturnStatementIsMissing() {
+        // given
+        var tree = Helper.prepareParser("function foo(): int { let x: int; x = 0; } foo();");
+        var ctxAnal = new ContextAnalysis(
+                Helper.getFuncs(tree),
+                Helper.getStructs(tree),
+                Helper.getEnums(tree)
+        );
+
+        // when / then
+        var e = assertThrows(RuntimeException.class, () -> ctxAnal.visit(tree));
+        assertEquals("Error in line 1:20 Function foo has to return something of type int.", e.getMessage());
     }
 }
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