diff --git a/libsrc/pet/waitvsync.s b/libsrc/pet/waitvsync.s
new file mode 100644
index 000000000..39b562e43
--- /dev/null
+++ b/libsrc/pet/waitvsync.s
@@ -0,0 +1,16 @@
+;
+; Written by Robin Harbron, requires 12" monitor
+;
+; void waitvsync (void);
+;
+
+        .export         _waitvsync
+
+        .include        "pet.inc"
+
+_waitvsync:
+@l1:
+        lda     VIA_PB
+        and     #%00100000
+        bne     @l1
+        rts