diff --git a/CMakeLists.txt b/CMakeLists.txt
index 52109fb..16599e4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -46,6 +46,6 @@ add_executable(Flup
     submodules/utilitiec/src/utf8/utf-8.h
     submodules/utilitiec/src/cmakegen.sh
     submodules/utilitiec/src/CMakeLists.txt
-    submodules/utilitiec/src/errorcodes.h)
+    submodules/utilitiec/src/errorcodes.h src/error-message.c src/error-message.h)
 
 target_link_libraries(Flup m)
diff --git a/src/builtin-functions.c b/src/builtin-functions.c
index 2ede45d..4f238db 100644
--- a/src/builtin-functions.c
+++ b/src/builtin-functions.c
@@ -20,19 +20,21 @@
 #include "builtin-functions.h"
 
 #include "value.h"
+#include "error-message.h"
+#include "interpreter.h"
 
 #include <stdlib.h>
 #include <stdio.h>
 #include <inttypes.h>
 
-int BuiltinFunction_Equality(CallFrame* top_frame)
+int BuiltinFunction_Equality(CallFrame* top_frame, Interpreter* interpreter)
 {
 	Value v1;
 	Value v2;
 
 	CallFrame_StackPop(top_frame, &v1);
 	if (CallFrame_StackPop(top_frame, &v2) != EXIT_SUCCESS) {
-		// TODO: Error message
+		ErrorMessage_EmptyStackError(interpreter, top_frame);
 		return EXIT_FAILURE;
 	}
 
@@ -45,18 +47,18 @@ int BuiltinFunction_Equality(CallFrame* top_frame)
 
 }
 
-int BuiltinFunction_Plus(CallFrame* top_frame)
+int BuiltinFunction_Plus(CallFrame* top_frame, Interpreter* interpreter)
 {
 	Value v1;
 	Value v2;
 
 	CallFrame_StackPop(top_frame, &v1);
 	if (CallFrame_StackPop(top_frame, &v2) != EXIT_SUCCESS) {
-		// TODO: Error message
+		ErrorMessage_EmptyStackError(interpreter, top_frame);
 		return EXIT_FAILURE;
 	}
 	if (v1.type != v2.type) {
-		// TODO: Error message
+		ErrorMessage_IncompatibleTypesError(interpreter, top_frame, &v1, &v2);
 		return EXIT_FAILURE;
 	}
 
@@ -73,6 +75,7 @@ int BuiltinFunction_Plus(CallFrame* top_frame)
 			result.get.boolean = v2.get.boolean + v1.get.boolean;
 			break;
 		case VALUETYPE_OBJECT:
+			ErrorMessage_UnknownOperationForTypeError(interpreter, top_frame, "+", &v1);
 			return EXIT_FAILURE;
 		case VALUETYPE_BYTE:
 			return v1.get.byte + v2.get.byte;
@@ -82,18 +85,18 @@ int BuiltinFunction_Plus(CallFrame* top_frame)
 	return CallFrame_StackPush(top_frame, &result);
 }
 
-int BuiltinFunction_Multiply(CallFrame* top_frame)
+int BuiltinFunction_Multiply(CallFrame* top_frame, Interpreter* interpreter)
 {
 	Value v1;
 	Value v2;
 
 	CallFrame_StackPop(top_frame, &v1);
 	if (CallFrame_StackPop(top_frame, &v2) != EXIT_SUCCESS) {
-		// TODO: Error message
+		ErrorMessage_EmptyStackError(interpreter, top_frame);
 		return EXIT_FAILURE;
 	}
 	if (v1.type != v2.type) {
-		// TODO: Error message
+		ErrorMessage_IncompatibleTypesError(interpreter, top_frame, &v1, &v2);
 		return EXIT_FAILURE;
 	}
 
@@ -110,6 +113,7 @@ int BuiltinFunction_Multiply(CallFrame* top_frame)
 			result.get.boolean = v2.get.boolean * v1.get.boolean;
 			break;
 		case VALUETYPE_OBJECT:
+			ErrorMessage_UnknownOperationForTypeError(interpreter, top_frame, "*", &v1);
 			return EXIT_FAILURE;
 		case VALUETYPE_BYTE:
 			return v1.get.byte * v2.get.byte;
@@ -119,18 +123,18 @@ int BuiltinFunction_Multiply(CallFrame* top_frame)
 	return CallFrame_StackPush(top_frame, &result);
 }
 
-int BuiltinFunction_Minus(CallFrame* top_frame)
+int BuiltinFunction_Minus(CallFrame* top_frame, Interpreter* interpreter)
 {
 	Value v1;
 	Value v2;
 
 	CallFrame_StackPop(top_frame, &v1);
 	if (CallFrame_StackPop(top_frame, &v2) != EXIT_SUCCESS) {
-		// TODO: Error message
+		ErrorMessage_EmptyStackError(interpreter, top_frame);
 		return EXIT_FAILURE;
 	}
 	if (v1.type != v2.type) {
-		// TODO: Error message
+		ErrorMessage_IncompatibleTypesError(interpreter, top_frame, &v1, &v2);
 		return EXIT_FAILURE;
 	}
 
@@ -147,6 +151,7 @@ int BuiltinFunction_Minus(CallFrame* top_frame)
 			result.get.boolean = v2.get.boolean - v1.get.boolean;
 			break;
 		case VALUETYPE_OBJECT:
+			ErrorMessage_UnknownOperationForTypeError(interpreter, top_frame, "-", &v1);
 			return EXIT_FAILURE;
 		case VALUETYPE_BYTE:
 			return v1.get.byte - v2.get.byte;
@@ -156,11 +161,12 @@ int BuiltinFunction_Minus(CallFrame* top_frame)
 	return CallFrame_StackPush(top_frame, &result);
 }
 
-int BuiltinFunction_Print(CallFrame* top_frame)
+int BuiltinFunction_Print(CallFrame* top_frame, Interpreter* interpreter)
 {
 	Value v1;
 
 	if (CallFrame_StackPop(top_frame, &v1) != EXIT_SUCCESS) {
+		ErrorMessage_EmptyStackError(interpreter, top_frame);
 		return EXIT_FAILURE;
 	}
 
@@ -197,9 +203,9 @@ int BuiltinFunction_Print(CallFrame* top_frame)
 	return EXIT_SUCCESS;
 }
 
-int BuiltinFunction_PrintLine(CallFrame* top_frame)
+int BuiltinFunction_PrintLine(CallFrame* top_frame, Interpreter* interpreter)
 {
-	if (BuiltinFunction_Print(top_frame)) {
+	if (BuiltinFunction_Print(top_frame, interpreter)) {
 		return EXIT_FAILURE;
 	} else {
 		puts("");
@@ -207,15 +213,17 @@ int BuiltinFunction_PrintLine(CallFrame* top_frame)
 	}
 }
 
-int BuiltinFunction_Duplicate(CallFrame* top_frame)
+int BuiltinFunction_Duplicate(CallFrame* top_frame, Interpreter* interpreter)
 {
 	Value v1;
 
 	if (CallFrame_StackPop(top_frame, &v1) != EXIT_SUCCESS) {
+		ErrorMessage_EmptyStackError(interpreter, top_frame);
 		return EXIT_FAILURE;
 	}
 
 	if (CallFrame_StackPush(top_frame, &v1) || CallFrame_StackPush(top_frame, &v1)) {
+		ErrorMessage_StackPushError(interpreter, top_frame);
 		return EXIT_FAILURE;
 	}
 
diff --git a/src/builtin-functions.h b/src/builtin-functions.h
index fc62b55..1e32102 100644
--- a/src/builtin-functions.h
+++ b/src/builtin-functions.h
@@ -22,15 +22,16 @@
 
 #include "callframe.h"
 #include "tokenizer.h"
+#include "interpreter.h"
 
 
-int BuiltinFunction_Minus(CallFrame* top_frame);
-int BuiltinFunction_Plus(CallFrame* top_frame);
-int BuiltinFunction_Multiply(CallFrame* top_frame);
-int BuiltinFunction_Equality(CallFrame* top_frame);
-int BuiltinFunction_Print(CallFrame* top_frame);
-int BuiltinFunction_PrintLine(CallFrame* top_frame);
-int BuiltinFunction_Duplicate(CallFrame* top_frame);
+int BuiltinFunction_Minus(CallFrame* top_frame, Interpreter* interpreter);
+int BuiltinFunction_Plus(CallFrame* top_frame, Interpreter* interpreter);
+int BuiltinFunction_Multiply(CallFrame* top_frame, Interpreter* interpreter);
+int BuiltinFunction_Equality(CallFrame* top_frame, Interpreter* interpreter);
+int BuiltinFunction_Print(CallFrame* top_frame, Interpreter* interpreter);
+int BuiltinFunction_PrintLine(CallFrame* top_frame, Interpreter* interpreter);
+int BuiltinFunction_Duplicate(CallFrame* top_frame, Interpreter* interpreter);
 
 
 #endif
diff --git a/src/error-message.c b/src/error-message.c
new file mode 100644
index 0000000..624831f
--- /dev/null
+++ b/src/error-message.c
@@ -0,0 +1,56 @@
+//
+// Created by UserAlex on 10.10.2024.
+//
+
+#include "error-message.h"
+#include "interpreter.h"
+#include "value.h"
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdarg.h>
+
+
+void ErrorMessage_err(char* message, Interpreter* interpreter, CallFrame* top_frame)
+{
+	Token* token = Interpreter_ExpectToken(interpreter, top_frame, top_frame->instruction_pointer + 1);
+	printf("Error in line: % " PRIi32 ", column: %" PRIi32, token->context.row, token->context.col);
+	printf(": %s\n", message);
+}
+
+void ErrorMessage_EmptyStackError(Interpreter* interpreter, CallFrame* top_frame)
+{
+	ErrorMessage_err("Trying to pop from stack while stack is empty", interpreter, top_frame);
+
+}
+
+void ErrorMessage_StackPushError(Interpreter* interpreter, CallFrame* top_frame)
+{
+	ErrorMessage_err("Error while trying to push to stack", interpreter, top_frame);
+}
+
+
+void ErrorMessage_IncompatibleTypesError(Interpreter* interpreter, CallFrame* top_frame, Value* expect, Value* got)
+{
+	// TODO: die nächsten drei Zeilen kommen in den anderen Funktionen auch so ähnlich vor -> da am besten in Funktion auslagern
+	size_t total_length = snprintf(NULL, 0, "Incompatible types, expected %s but got %s", Value_ToString(expect->type), Value_ToString(got->type));
+	char string[total_length + 1];
+	snprintf(string, total_length + 1, "Incompatible types, expected %s but got %s", Value_ToString(expect->type), Value_ToString(got->type));
+	ErrorMessage_err( string, interpreter, top_frame);
+}
+
+void ErrorMessage_UnknownOperationForTypeError(Interpreter* interpreter, CallFrame* top_frame, char* operation, Value* value)
+{
+	size_t total_length = snprintf(NULL, 0, "Unknown operation %s for type %s", operation, Value_ToString(value->type));
+	char string[total_length + 1];
+	snprintf(string, total_length + 1, "Unknown operation %s for type %s", operation, Value_ToString(value->type));
+	ErrorMessage_err( string, interpreter, top_frame);
+}
+
+void ErrorMessage_OutOfMemoryError(char* context, Interpreter* interpreter, CallFrame* top_frame)
+{
+	size_t total_length = snprintf(NULL, 0, "Out of memory: %s", context);
+	char string[total_length + 1];
+	snprintf(string, total_length + 1, "Out of memory: %s", context);
+	ErrorMessage_err(string, interpreter, top_frame);
+}
\ No newline at end of file
diff --git a/src/error-message.h b/src/error-message.h
new file mode 100644
index 0000000..eadaf89
--- /dev/null
+++ b/src/error-message.h
@@ -0,0 +1,40 @@
+/*
+ * This code is part of the programming language flup
+ * flup comes with ABSOLUTELY NO WARRANTY and is licensed under AGPL-3.0 or later.
+ *    Copyright (C) 2024  VegOwOtenks
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#ifndef FLUP_ERROR_MESSAGES_H
+#define FLUP_ERROR_MESSAGES_H
+
+#include "tokenizer.h"
+#include "interpreter.h"
+
+
+void ErrorMessage_err(char* message, Interpreter* interpreter, CallFrame* top_frame);
+
+void ErrorMessage_EmptyStackError(Interpreter* interpreter, CallFrame* top_frame);
+
+void ErrorMessage_StackPushError(Interpreter* interpreter, CallFrame* top_frame);
+
+void ErrorMessage_IncompatibleTypesError(Interpreter* interpreter, CallFrame* top_frame, Value* expect, Value* got);
+
+void ErrorMessage_UnknownOperationForTypeError(Interpreter* interpreter, CallFrame* top_frame, char* operation, Value* value);
+
+void ErrorMessage_OutOfMemoryError(char* context, Interpreter* interpreter, CallFrame* top_frame);
+
+#endif //FLUP_ERROR_MESSAGES_H
diff --git a/src/interpreter.c b/src/interpreter.c
index a66e8f5..92f51a2 100644
--- a/src/interpreter.c
+++ b/src/interpreter.c
@@ -1,6 +1,7 @@
 #include "interpreter.h"
 #include "builtin-functions.h"
 #include "object-type.h"
+#include "error-message.h"
 
 #include <stdio.h>
 #include <stdalign.h>
@@ -90,16 +91,17 @@ int Interpreter_ParseFunction(Interpreter* self, CallFrame* top_frame, size_t st
 		top_frame->instruction_pointer++;
 
 		if (parameter_type->type != TOKENTYPE_IDENTIFIER) {
-			// TODO: Error message
+			ErrorMessage_err("Expected identifier for parameter type-definition in function definition", self, top_frame);
 			return EXIT_FAILURE;
 		}
 		if (parameter_name->type != TOKENTYPE_IDENTIFIER) {
-			// TODO: Error message
+			ErrorMessage_err("Expected identifier for parameter name-declaration in function definition", self, top_frame);
 			return EXIT_FAILURE;
 		}
 
 		*pdef = CallFrame_Reserve(top_frame, sizeof(ParameterDefinition), alignof(ParameterDefinition));
 		if (*pdef == NULL) {
+			ErrorMessage_OutOfMemoryError("Failed to reserve memory for CallFrame in Function parsefunction", self, top_frame);
 			return ENOMEM;
 		}
 
@@ -221,7 +223,7 @@ int  Interpreter_CallBuiltinFunction(Interpreter* self, CallFrame* parent_frame,
 	StringView function_name = name->get.identifier;
 	for (size_t i = 0; self->builtin_names[i] != NULL; i++) {
 		if (StringView_Equal(function_name, StringView_FromString(self->builtin_names[i]))) {
-			return self->builtin_functions[i](parent_frame);
+			return self->builtin_functions[i](parent_frame, self);
 		}
 	}
 
@@ -350,22 +352,22 @@ int Interpreter_ExecuteNext(Interpreter* self, size_t stop_token)
 
 		case TOKENTYPE_EQUALITY:
 		{
-			return BuiltinFunction_Equality(top_frame);
+			return BuiltinFunction_Equality(top_frame, self);
 		}
 
 		case TOKENTYPE_PLUS:
 		{
-			BuiltinFunction_Plus(top_frame);
+			BuiltinFunction_Plus(top_frame, self);
 			break;
 		}
 		case TOKENTYPE_MINUS:
 		{
-			BuiltinFunction_Minus(top_frame);
+			BuiltinFunction_Minus(top_frame, self);
 			break;
 		}
 		case TOKENTYPE_MULTIPLY:
 		{
-			BuiltinFunction_Multiply(top_frame);
+			BuiltinFunction_Multiply(top_frame, self);
 			break;
 		}
 
diff --git a/src/interpreter.h b/src/interpreter.h
index 4b48a25..a204dbf 100644
--- a/src/interpreter.h
+++ b/src/interpreter.h
@@ -11,7 +11,7 @@
 
 typedef struct Interpreter_s Interpreter;
 
-typedef int (*BuiltinFunction)(CallFrame *);
+typedef int (*BuiltinFunction)(CallFrame *, Interpreter* interpreter);
 
 struct Interpreter_s {
 	const char** builtin_names;
@@ -29,4 +29,6 @@ int Interpreter_Create(Interpreter* self, DynamicArray* tokens);
 int Interpreter_Interpret(Interpreter* self);
 void Interpreter_Destroy(Interpreter* self);
 
+Token* Interpreter_ExpectToken(Interpreter* self, CallFrame* top_frame, size_t stop_index);
+
 #endif //FLUP_INTERPRETER_H
diff --git a/src/main.c b/src/main.c
index 3d83bea..8f48405 100644
--- a/src/main.c
+++ b/src/main.c
@@ -20,15 +20,69 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <inttypes.h>
 
 #include "../submodules/utilitiec/src/argumentc/argumentc.h"
 #include "interpreter.h"
 #include "tokenizer.h"
 
+//Debug
+//Temp
+
+void tokencontent_tostring(Token* token) {
+	switch (token->type) {
+		case TOKENTYPE_INTEGER:
+			printf("%" PRIi64, token->get.integer);
+			break;
+		case TOKENTYPE_DOUBLE:
+			printf("%f", token->get.decimal);
+			break;
+		case TOKENTYPE_IDENTIFIER:
+		case TOKENTYPE_COMMENT:
+		case TOKENTYPE_STRING:
+		case TOKENTYPE_ERROR:
+			printf("%s", token->get.identifier);
+			break;
+		case TOKENTYPE_NONE:
+		case TOKENTYPE_LEFT_BRACE:
+		case TOKENTYPE_RIGHT_BRACE:
+		case TOKENTYPE_AMPERSAND:
+		case TOKENTYPE_PLUS:
+		case TOKENTYPE_MINUS:
+		case TOKENTYPE_MULTIPLY:
+		case TOKENTYPE_DIVIDE:
+		case TOKENTYPE_PIPE:
+		case TOKENTYPE_ARROW:
+		case TOKENTYPE_COLON:
+		case TOKENTYPE_SEMICOLON:
+		case TOKENTYPE_EQUALITY:
+		case TOKENTYPE_INEQUALITY:
+		case TOKENTYPE_LESSTHAN:
+		case TOKENTYPE_LESSEQUAL:
+		case TOKENTYPE_GREATERTHAN:
+		case TOKENTYPE_GREATEREQUAL:
+		case TOKENTYPE_COMMA:
+		case TOKENTYPE_BIND:
+		case TOKENTYPE_AS:
+		case TOKENTYPE_LEFT_PAREN:
+		case TOKENTYPE_RIGHT_PAREN:
+			break;
+	}
+}
+
+void print_token(Token* token) {
+	printf("Token: type: %s, TokenContent: ", TokenType_ToString(token->type));
+	tokencontent_tostring(token);
+	printf(" , contex: row: %i, col: %i\n", token->context.row, token->context.col);
+}
+
 int tokenize_all(StringView source, DynamicArray* a)
 {
+	TokenContext context = {.row = 1, .col = 1};
 	Token t;
-	while ((t = Tokenizer_NextToken(&source)).type != TOKENTYPE_NONE) {
+	while ((t = Tokenizer_NextToken(&source, &context)).type != TOKENTYPE_NONE) {
+		//Debug
+		print_token(&t);
 		int append_code = DynamicArray_Append(a, &t);
 		if (append_code) return append_code;
 		if (t.type == TOKENTYPE_ERROR) break;
diff --git a/src/tokenizer.c b/src/tokenizer.c
index 3a95999..db4a535 100644
--- a/src/tokenizer.c
+++ b/src/tokenizer.c
@@ -53,27 +53,40 @@ static Token _Tokenizer_ParseDouble(bool negative, StringView integerPart, Strin
 	};
 }
 
-static Token _Tokenizer_NumberToken(StringView* source)
+static Token _Tokenizer_NumberToken(StringView* source, TokenContext* current)
 {
+	uint32_t token_length = 0;
 	bool negative = false;
 	if (StringView_StartsWith(*source, StringView_FromString("-"))) {
 		negative = true;
 		*source = StringView_Drop(*source, 1);
+		token_length++;
 	}
 
 	StringView integerPart = StringViewOfNumberTillNextNonDigit(source);
+	token_length += integerPart.length;
 	bool has_point = false;
 	if (source->length != 0 && source->source[0] == '.') {
 		*source = StringView_Drop(*source, 1);
 		has_point = true;
+		token_length++;
 	}
 	StringView decimalPart = StringViewOfNumberTillNextNonDigit(source);
+	token_length += decimalPart.length;
+
+	Token token;
 
 	if (has_point) {
-		return _Tokenizer_ParseDouble(negative, integerPart, decimalPart);
+		token = _Tokenizer_ParseDouble(negative, integerPart, decimalPart);
 	} else {
-		return _Tokenizer_ParseInt64(negative, integerPart);
+		token = _Tokenizer_ParseInt64(negative, integerPart);
 	}
+
+	//udpate context
+	token.context = *current;
+	current->col += token_length;
+
+	return token;
 }
 
 static bool _Tokenizer_IdentifierLetter(char c)
@@ -81,17 +94,21 @@ static bool _Tokenizer_IdentifierLetter(char c)
 	return isalnum(c);
 }
 
-static Token _Tokenizer_IdentifierToken(StringView* source)
+static Token _Tokenizer_IdentifierToken(StringView* source, TokenContext* current)
 {
 	StringView identifier = StringView_TakeWhile(*source, _Tokenizer_IdentifierLetter);
 	*source = StringView_Drop(*source, identifier.length);
 
-	return (Token) {
+	Token token =  (Token) {
 		.type = TOKENTYPE_IDENTIFIER,
 		.get = {
 			.identifier = identifier,
-		}
+		},
+		.context = *current
 	};
+
+	current->col += identifier.length;
+	return token;
 }
 
 static bool _Tokenizer_ContinueCommentFunction(char c)
@@ -104,7 +121,7 @@ static bool _Tokenizer_ContinueStringFunction(char c)
 	return c != '"';
 }
 
-static Token _Tokenizer_SimpleToken(StringView* source)
+static Token _Tokenizer_SimpleToken(StringView* source, TokenContext* current)
 {
 	const char* literal_table[] = { "{", "}", "&", ":", "+", "->", "-", "*", "/", "|", "==", "!=", "<", "<=", ">", ">=", ",", ";", "bind", "as", "(", ")" };
 	const enum TokenType type_table[] = { 
@@ -136,26 +153,32 @@ static Token _Tokenizer_SimpleToken(StringView* source)
 		StringView literal_view = StringView_FromString(literal_table[i]);
 		if (StringView_StartsWith(*source, literal_view)) {
 			*source = StringView_Drop(*source, literal_view.length);
-			return (Token) {
+			Token token = (Token) {
 				.type = type_table[i],
-				.get = { .identifier = STRINGVIEW_NONE }
+				.get = { .identifier = STRINGVIEW_NONE },
+				.context = *current
 			};
+			current->col += literal_view.length;
+			return token;
 		}
 	}
 	return TOKEN_NONE;
 }
 
-Token _Tokenizer_CommentToken(StringView* source)
+Token _Tokenizer_CommentToken(StringView* source, TokenContext* current)
 {
 	StringView comment = StringView_SpanWhile(source, _Tokenizer_ContinueCommentFunction);
 
-	return (Token) {
+	Token token = (Token) {
 		.type = TOKENTYPE_COMMENT,
 		.get = { .identifier = comment },
+		.context = *current
 	};
+	current->col += comment.length;
+	return token;
 }
 
-Token _Tokenizer_StringToken(StringView* source)
+Token _Tokenizer_StringToken(StringView* source, TokenContext* current)
 {
 	*source = StringView_Drop(*source, 1);
 	StringView string = StringView_SpanWhile(source, _Tokenizer_ContinueStringFunction);
@@ -163,15 +186,34 @@ Token _Tokenizer_StringToken(StringView* source)
 	string.length += 2;
 	*source = StringView_Drop(*source, 1);
 
-	return (Token) {
+	Token token = (Token) {
 		.type = TOKENTYPE_STRING,
 		.get = { .identifier = string },
+		.context = *current
 	};
+
+	size_t newline_count = StringView_Count(string, StringView_FromString("\n"));
+	if(newline_count == 0) {
+		current->col += string.length;
+	} else {
+		current->row += newline_count;
+		current->col = 1;
+		StringView last_newline_split;
+		StringView_LastSplit(&last_newline_split, &string, StringView_FromString("\n"));
+		current->col += last_newline_split.length;
+	}
+	return token;
 }
 
-Token Tokenizer_NextToken(StringView* source)
+Token Tokenizer_NextToken(StringView* source, TokenContext* context)
 {
 	while (source->length != 0 && isspace(source->source[0])) {
+		if (source->source[0] == '\n') {
+			context->col = 1;
+			context->row++;
+		} else {
+			context->col++;
+		}
 		0[source] = StringView_Slice(*source, 1, source->length);
 	}
 
@@ -180,7 +222,7 @@ Token Tokenizer_NextToken(StringView* source)
 	}
 
 	{
-		Token simple_token = _Tokenizer_SimpleToken(source);
+		Token simple_token = _Tokenizer_SimpleToken(source, context);
 		if (simple_token.type != TOKENTYPE_NONE) {
 			return simple_token;
 		}
@@ -188,16 +230,18 @@ Token Tokenizer_NextToken(StringView* source)
 
 	if (isdigit(source->source[0]) || StringView_StartsWith(*source, StringView_FromString("-"))) {
 		// parse int/double
-		return _Tokenizer_NumberToken(source);
+		return _Tokenizer_NumberToken(source, context);
 	} else if (isalpha(source->source[0])) {
 		// parse name
-		return _Tokenizer_IdentifierToken(source);
+		return _Tokenizer_IdentifierToken(source, context);
 	} else if (StringView_StartsWith(*source, StringView_FromString("#"))) {
-			return _Tokenizer_CommentToken(source);
+			return _Tokenizer_CommentToken(source, context);
 	} else if (StringView_StartsWith(*source, StringView_FromString("\""))) {
-			return _Tokenizer_StringToken(source);
+			return _Tokenizer_StringToken(source, context);
 	} else {
-		return (Token) {.type = TOKENTYPE_ERROR, .get = {.error = *source } };
+		Token non_token = (Token) {.type = TOKENTYPE_ERROR, .get = {.error = *source }, .context = *context };
+		context->col++;
+		return non_token;
 	}
 }
 
diff --git a/src/tokenizer.h b/src/tokenizer.h
index d8ea088..bb05337 100644
--- a/src/tokenizer.h
+++ b/src/tokenizer.h
@@ -43,15 +43,21 @@ union TokenContent {
 	double     decimal;
 };
 
+typedef struct TokenContext_s {
+	uint32_t row;
+	uint32_t col;
+} TokenContext;
+
 typedef struct Token_s {
 	enum TokenType type;
 	union TokenContent get;
+	TokenContext context;
 } Token;
 
 
 #define TOKEN_NONE ((Token) {.type = TOKENTYPE_NONE, .get = {.error = STRINGVIEW_NONE } } )
 
-Token Tokenizer_NextToken(StringView* source);
+Token Tokenizer_NextToken(StringView* source, TokenContext* context);
 const char* TokenType_ToString(enum TokenType type);
 
 #endif //header guard
diff --git a/src/value.c b/src/value.c
index f0edbca..d90f0ee 100644
--- a/src/value.c
+++ b/src/value.c
@@ -57,24 +57,23 @@ bool Value_Equal(Value* v1, Value* v2)
 	return false;
 }
 
+const char * Value_ToString(enum ValueType type) {
+	const enum ValueType type_mapping[] = {VALUETYPE_INT64, VALUETYPE_DOUBLE, VALUETYPE_BOOLEAN, VALUETYPE_BOOLEAN};
+	const char* name_mapping[] = {"int", "double", "bool", "boolean"};
+
+	for (size_t i = 0; i < sizeof(name_mapping) / sizeof(name_mapping[0]); i++) {
+		if (type == type_mapping[i] ) {
+			return name_mapping[i];
+		}
+	}
+	return NULL;
+}
+
 bool Value_TypeMatchesStringName(enum ValueType type, StringView type_name)
 {
 	if (StringView_Equal(type_name, StringView_FromString("any"))) {
 		return true;
 	}
-
-	const enum ValueType type_mapping[] = {VALUETYPE_INT64, VALUETYPE_DOUBLE, VALUETYPE_BOOLEAN, VALUETYPE_BOOLEAN};
-	const char* name_mapping[] = {"int", "double", "bool", "boolean"};
-
-	for (size_t i = 0; i < sizeof(name_mapping) / sizeof(name_mapping[0]); i++) {
-		if (1 == 1
-			&& type == type_mapping[i]
-			&& StringView_Equal(type_name, StringView_FromString(name_mapping[i]))
-				) {
-			return true;
-		}
-	}
-
-	return false;
+	return StringView_Equal(type_name, StringView_FromString(Value_ToString(type)));
 }
 
diff --git a/src/value.h b/src/value.h
index 855facb..7d57101 100644
--- a/src/value.h
+++ b/src/value.h
@@ -43,6 +43,8 @@ typedef struct Value_s {
 
 bool Value_IsTruthy(Value* v);
 bool Value_Equal(Value* v1, Value* v2);
+
+const char * Value_ToString(enum ValueType type);
 bool Value_TypeMatchesStringName(enum ValueType type, StringView type_name);
 
 
diff --git a/test-inputs/efficient-fibonacci.flup b/test-inputs/efficient-fibonacci.flup
index 9ff7b63..ad0a5e9 100644
--- a/test-inputs/efficient-fibonacci.flup
+++ b/test-inputs/efficient-fibonacci.flup
@@ -3,7 +3,7 @@ fib: int n -> int
 		| iterations 0 == -> a b +
 		| 1               -> a b + println	b a b + iterations 1 - fib
 		;
-	1 1 n fib
+	0 1 n fib
     ;
 
 50 fib println
diff --git a/test-inputs/test_error_messages.flup b/test-inputs/test_error_messages.flup
new file mode 100644
index 0000000..2679ff6
--- /dev/null
+++ b/test-inputs/test_error_messages.flup
@@ -0,0 +1,13 @@
+# test stack pop while stack empty in builtin-function equal
+# 0 ==
+
+# test incompatible types
+# 1 1.1 +
+
+# test expected identifier for type in function param list
+# a: 1 b -> int
+# 	|1 -> 0
+
+# test expected identifier for name in function param list
+a: int 1 -> int
+    |1 -> 0
\ No newline at end of file