diff --git a/src/builtin-functions.c b/src/builtin-functions.c
index 119e75b..adb3f0e 100644
--- a/src/builtin-functions.c
+++ b/src/builtin-functions.c
@@ -23,6 +23,7 @@
 
 #include <stdlib.h>
 #include <stdio.h>
+#include <inttypes.h>
 
 int BuiltinFunction_Equality(CallFrame* top_frame)
 {
@@ -77,6 +78,39 @@ int BuiltinFunction_Plus(CallFrame* top_frame)
 	return CallFrame_StackPush(top_frame, &result);
 }
 
+int BuiltinFunction_Multiply(CallFrame* top_frame)
+{
+	Value v1;
+	Value v2;
+
+	CallFrame_StackPop(top_frame, &v1);
+	if (CallFrame_StackPop(top_frame, &v2) != EXIT_SUCCESS) {
+		// TODO: Error message
+		return EXIT_FAILURE;
+	}
+	if (v1.type != v2.type) {
+		// TODO: Error message
+		return EXIT_FAILURE;
+	}
+
+	Value result;
+	result.type = v1.type;
+	switch (v1.type) {
+		case VALUETYPE_INT64:
+			result.get.i64 = v2.get.i64 * v1.get.i64;
+			break;
+		case VALUETYPE_DOUBLE:
+			result.get.f64 = v2.get.f64 * v1.get.f64;
+			break;
+		case VALUETYPE_BOOLEAN:
+			result.get.boolean = v2.get.boolean * v1.get.boolean;
+			break;
+	}
+
+	top_frame->instruction_pointer++;
+	return CallFrame_StackPush(top_frame, &result);
+}
+
 int BuiltinFunction_Minus(CallFrame* top_frame)
 {
 	Value v1;
@@ -121,7 +155,7 @@ int BuiltinFunction_PrintLine(CallFrame* top_frame)
 
 	switch (v1.type) {
 		case VALUETYPE_INT64:
-			printf("%i\n", v1.get.i64);
+			printf("%" PRIi64 "\n", v1.get.i64);
 			break;
 		case VALUETYPE_DOUBLE:
 			printf("%f\n", v1.get.f64);
diff --git a/src/builtin-functions.h b/src/builtin-functions.h
index cd690a3..fb919a0 100644
--- a/src/builtin-functions.h
+++ b/src/builtin-functions.h
@@ -26,9 +26,10 @@
 
 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_PrintLine(CallFrame* top_frame);
 int BuiltinFunction_Duplicate(CallFrame* top_frame);
 
 
-#endif
\ No newline at end of file
+#endif
diff --git a/src/interpreter.c b/src/interpreter.c
index 1630364..d8c9d01 100644
--- a/src/interpreter.c
+++ b/src/interpreter.c
@@ -360,6 +360,11 @@ int Interpreter_ExecuteNext(Interpreter* self, size_t stop_token)
 			BuiltinFunction_Minus(top_frame);
 			break;
 		}
+		case TOKENTYPE_MULTIPLY:
+		{
+			BuiltinFunction_Multiply(top_frame);
+			break;
+		}
 
 		case TOKENTYPE_BIND:
 		{
@@ -478,7 +483,6 @@ int Interpreter_ExecuteNext(Interpreter* self, size_t stop_token)
 		case TOKENTYPE_LEFT_BRACE:
 		case TOKENTYPE_RIGHT_BRACE:
 		case TOKENTYPE_AMPERSAND:
-		case TOKENTYPE_MULTIPLY:
 		case TOKENTYPE_DIVIDE:
 		case TOKENTYPE_ARROW:
 		case TOKENTYPE_COLON:
@@ -490,7 +494,7 @@ int Interpreter_ExecuteNext(Interpreter* self, size_t stop_token)
 		case TOKENTYPE_COMMA:
 		case TOKENTYPE_LEFT_PAREN:
 		case TOKENTYPE_RIGHT_PAREN:
-			fprintf(stderr, "Unexpected token with type: %s\n, continuing with next token...\n", TokenType_ToString(t->type));
+			fprintf(stderr, "Unexpected token with type: %s, continuing with next token...\n", TokenType_ToString(t->type));
 			top_frame->instruction_pointer++;
 			break;
 
diff --git a/src/main.c b/src/main.c
index 4e9bba1..3d83bea 100644
--- a/src/main.c
+++ b/src/main.c
@@ -56,10 +56,10 @@ char* load_file_string(StringView path)
 		return NULL;
 	}
 
-    if (fseek(stream, 0, SEEK_SET)) {
-        perror("fseek");
-        return NULL;
-    }
+	if (fseek(stream, 0, SEEK_SET)) {
+		perror("fseek");
+		return NULL;
+	}
 
 	char* buffer = malloc(length + 1);
 	if (buffer == NULL) {
@@ -68,9 +68,8 @@ char* load_file_string(StringView path)
 	}
 
 	size_t objects_read = fread(buffer, 1, length, stream);
-	if (objects_read != length) {
+	if (objects_read != (size_t) length) {
 		fprintf(stderr, "Fatal Error: Failed read %li bytes from script file, got only %li\n", length, objects_read);
-        ;
 		free(buffer);
 		return NULL;
 	}