diff --git a/libsrc/apple2/ser/a2.ssc.s b/libsrc/apple2/ser/a2.ssc.s
index e0cd94597..d49bf3526 100644
--- a/libsrc/apple2/ser/a2.ssc.s
+++ b/libsrc/apple2/ser/a2.ssc.s
@@ -199,7 +199,7 @@ SER_OPEN:
         asl
         asl
         asl
-        adc     Offset                  ; Assume carry to be clear
+        adc     #Offset                 ; Assume carry to be clear
         tax
 
         ; Check if the handshake setting is valid