diff --git a/libsrc/supervision/joy/supervision-stdjoy.s b/libsrc/supervision/joy/supervision-stdjoy.s
index d233a8600..5d6e23bc0 100644
--- a/libsrc/supervision/joy/supervision-stdjoy.s
+++ b/libsrc/supervision/joy/supervision-stdjoy.s
@@ -77,5 +77,6 @@ COUNT:
 
 READJOY:
         lda     sv_control
+	eor     #$FF
         ldx     #0
         rts