diff --git a/src/interpreter.c b/src/interpreter.c
index 747389d..72ad6b3 100644
--- a/src/interpreter.c
+++ b/src/interpreter.c
@@ -73,6 +73,16 @@ Token* Interpreter_ExpectToken(Interpreter* self, CallFrame* top_frame, size_t s
 	return Interpreter_GetToken(self, top_frame->instruction_pointer);
 }
 
+bool is_begin_of_nested_function_definition(Interpreter* self, CallFrame* top_frame, size_t stop_index) {
+	Token* possible_colon = Interpreter_ExpectToken(self, top_frame, stop_index);
+	return possible_colon != NULL && possible_colon->type == TOKENTYPE_COLON;
+}
+
+bool is_end_of_nested_function_definition(Interpreter* self, CallFrame* top_frame, size_t stop_index) {
+	Token* possible_semicolon = Interpreter_ExpectToken(self, top_frame, stop_index);
+	return possible_semicolon != NULL && possible_semicolon->type == TOKENTYPE_SEMICOLON;
+}
+
 int Interpreter_ParseFunction(Interpreter* self, CallFrame* top_frame, size_t stop_index)
 {
 	FlupFunction* f = CallFrame_Reserve(top_frame, sizeof(FlupFunction), alignof(FlupFunction));
@@ -138,11 +148,14 @@ int Interpreter_ParseFunction(Interpreter* self, CallFrame* top_frame, size_t st
 		return EXIT_FAILURE;
 	}
 
+    int count_nested_functions = 0;
+
 	FlupFunctionAlternative** fdef = &f->alternatives;
 	while (alternative_start->type == TOKENTYPE_PIPE) {
-		top_frame->instruction_pointer++;
+		top_frame->instruction_pointer++; // pipe Token überspringen
 		size_t condition_start = top_frame->instruction_pointer;
 
+		// condition parsing
 		Token* current;
 		do {
 			current = Interpreter_ExpectToken(self, top_frame, stop_index);
@@ -151,7 +164,13 @@ int Interpreter_ParseFunction(Interpreter* self, CallFrame* top_frame, size_t st
 				return EXIT_FAILURE;
 			}
 			// TODO: Count inner colon and semicolon to allow for nested functions
-		} while (current->type != TOKENTYPE_ARROW);
+            if(is_begin_of_nested_function_definition(self, top_frame, stop_index)) {
+                count_nested_functions++;
+            }
+			if(is_end_of_nested_function_definition(self, top_frame, stop_index)) {
+				count_nested_functions--;
+			}
+		} while (current->type != TOKENTYPE_ARROW || count_nested_functions != 0);
 		size_t condition_end = top_frame->instruction_pointer - 2;
 
 		size_t body_start = top_frame->instruction_pointer;
@@ -748,9 +767,10 @@ int Interpreter_RunFrame(Interpreter* self)
 			return EXIT_FAILURE;
 		}
 
-		// char function_name[top_frame->self_function->name.length + 1];
-		// memset(function_name, 0, sizeof(function_name));
-		// StringView_Paste(function_name, top_frame->self_function->name);
+		char function_name[top_frame->self_function->name.length + 1];
+		memset(function_name, 0, sizeof(function_name));
+		StringView_Paste(function_name, top_frame->self_function->name);
+		printf("%s\n", function_name);
 
 		if (! _are_types_compatible(return_value.type, top_frame->self_function->return_type)) {
 			// TODO: Error message
diff --git a/src/main.c b/src/main.c
index f90263d..ab9e660 100644
--- a/src/main.c
+++ b/src/main.c
@@ -39,7 +39,7 @@ int tokenize_all(StringView source, DynamicArray* a)
 
 char* load_file_string(StringView path)
 {
-	FILE* stream = fopen(path.source, "r");
+	FILE* stream = fopen(path.source, "rb");
 	if (stream == NULL) {
 		fprintf(stderr, "Fatal Error: Failed to open file at %*s\n", (int) path.length, path.source);
 		return NULL;
@@ -56,7 +56,10 @@ char* load_file_string(StringView path)
 		return NULL;
 	}
 
-	rewind(stream);
+    if (fseek(stream, 0, SEEK_SET)) {
+        perror("fseek");
+        return NULL;
+    }
 
 	char* buffer = malloc(length + 1);
 	if (buffer == NULL) {
@@ -64,9 +67,10 @@ char* load_file_string(StringView path)
 		return NULL;
 	}
 
-	size_t objects_read = fread(buffer, length, 1, stream);
-	if (objects_read != 1) {
+	size_t objects_read = fread(buffer, 1, length, stream);
+	if (objects_read != length) {
 		fprintf(stderr, "Fatal Error: Failed read %li bytes from script file, got only %li\n", length, objects_read);
+        ;
 		free(buffer);
 		return NULL;
 	}
diff --git a/test-inputs/innere_function_definition.flup b/test-inputs/innere_function_definition.flup
new file mode 100644
index 0000000..a6f835b
--- /dev/null
+++ b/test-inputs/innere_function_definition.flup
@@ -0,0 +1,25 @@
+add: int a int b -> int
+    | 1 -> a b +
+    ;
+
+ad: int a int b -> int
+    | 1 -> a b +
+    ;
+
+fuenf: int a -> int
+    | 1 -> a
+    ;
+
+drei: int a -> int
+    | 1 -> a
+    ;
+
+test: int a -> int
+    | fb: int b -> int
+        | 1 b == -> 0 0 add
+        | 1 1 == -> 1 0 ad
+        ;
+        a fb ->  1 drei
+    | 1 1 == -> 3 fb
+    ;
+0 test
\ No newline at end of file