diff --git a/src/syscalls.c b/src/syscalls.c
index 4153084..c36954c 100644
--- a/src/syscalls.c
+++ b/src/syscalls.c
@@ -20,7 +20,7 @@ size_t mmap(syscall_arg_t arg_location, syscall_arg_t arg_length, syscall_arg_t
     {
         return EINVALIDARG;
     }
-    else if(location == NULL)
+    else if(location == (unsigned long)NULL)
     {
         return ENULLPTR;
     }