diff --git a/lang/cem/cemcom.ansi/ch3.c b/lang/cem/cemcom.ansi/ch3.c
index 8f717031..b6fed17f 100644
--- a/lang/cem/cemcom.ansi/ch3.c
+++ b/lang/cem/cemcom.ansi/ch3.c
@@ -531,7 +531,7 @@ legal_mixture(tp, otp, diag)
 	}
 
 	if (prot->pl_flag & PL_ELLIPSIS) {
-		if (diag && !(prot->pl_flag & PL_ERRGIVEN)) {
+		if (prot->pl_flag & PL_ERRGIVEN) {
 			if (pl)
 				error("illegal ellipsis terminator");
 			else	error("ellipsis terminator in previous (prototype) declaration");