diff --git a/headers/private/kernel/util/syscall_args.h b/headers/private/kernel/util/syscall_args.h
index f988b8b172..aae8001f7d 100644
--- a/headers/private/kernel/util/syscall_args.h
+++ b/headers/private/kernel/util/syscall_args.h
@@ -5,13 +5,19 @@
 
 #include <vm.h>
 
+// Hack to be able to use the CHECK_USER_ADDRESS macro when compiling for R5.
+#ifdef R5_MEMORY_LAYOUT
+#	undef KERNEL_BASE
+#	define KERNEL_BASE 0x0
+#endif
+
 // copy_ref_var_from_user
 template<typename T>
 inline
 status_t
 copy_ref_var_from_user(T *user, T &kernel)
 {
-	if (CHECK_USER_ADDRESS(user))
+	if (!CHECK_USER_ADDRESS(user))
 		return B_BAD_ADDRESS;
 	return user_memcpy(&kernel, user, sizeof(T));
 }
@@ -22,7 +28,7 @@ inline
 status_t
 copy_ref_var_to_user(T &kernel, T *user)
 {
-	if (CHECK_USER_ADDRESS(user))
+	if (!CHECK_USER_ADDRESS(user))
 		return B_BAD_ADDRESS;
 	return user_memcpy(user, &kernel, sizeof(T));
 }