diff --git a/common/common.asm b/common/common.asm
index e01413b..1a5b50c 100644
--- a/common/common.asm
+++ b/common/common.asm
@@ -599,10 +599,12 @@ _3	JSR _CMPDC	; is D < C?
 	ROL _RB+3
 	BCC _3
 	; carry is set, means a real overflow condition
-	LDA _R0+3,X
-	ORA #_F_O
+	LDA #$FF	; set to the maximum
+	STA _R0,X
+	STA _R0+1,X
+	STA _R0+2,X
+	LDA #_MAX_V|_F_O
 	STA _R0+3,X
-	BEQ _4
 	JMP _9
 _4	LDA _RB		; is RB > 0?
 	ORA _RB+1
diff --git a/common/common.h b/common/common.h
index 76e37c2..f314054 100644
--- a/common/common.h
+++ b/common/common.h
@@ -131,6 +131,7 @@ _MOD_C	= $e0
 _EXT_C	= $f0
 
 ; common constants
+_MAX_V	= $3f		; i.e. the $3f part of $3fffffff
 
 ; plus and minus 1 for increment and decrement
 _PLS_1	= %00000100	; i.e. the $04 part of $00000400