diff --git a/c64/basic/peek_pointer_null_check.s b/c64/basic/peek_pointer_null_check.s
index a476ae53..ff30acfb 100644
--- a/c64/basic/peek_pointer_null_check.s
+++ b/c64/basic/peek_pointer_null_check.s
@@ -4,9 +4,11 @@
 peek_pointer_null_check:
 	ldy #$00
 	jsr peek_under_roms
+	cmp #$00
 	bne ptr_not_null
 	iny
 	jsr peek_under_roms
+	cmp #$00
 	bne ptr_not_null
 
 	;; Pointer is NULL