diff --git a/src/std/string.c b/src/std/string.c
index bcc9cf0..3c6119f 100644
--- a/src/std/string.c
+++ b/src/std/string.c
@@ -113,7 +113,7 @@ void ARC_String_Append(ARC_String **string, ARC_String *append){
 }
 
 void ARC_String_AppendCString(ARC_String **string, const char *cstring, uint64_t length){
-    char *data = (char *)malloc(sizeof((*string)->length + length + 1));
+    char *data = (char *)malloc(sizeof(char) * ((*string)->length + length + 1));
 
     strncpy(data, (*string)->data, (*string)->length);
     strncpy(data + (*string)->length, cstring, length);