1 files changed, 3 insertions, 0 deletions
diff --git a/op.c b/op.c
index 207e762b80..7d28e36dd0 100644
--- a/op.c
+++ b/op.c
@@ -1137,6 +1137,9 @@ Perl_scalarvoid(pTHX_ OP *o)
 	else {
 	    if (ckWARN(WARN_VOID)) {
 		useless = "a constant";
+		/* the constants 0 and 1 are permitted as they are
+		   conventionally used as dummies in constructs like
+		        1 while some_condition_with_side_effects;  */
 		if (SvNIOK(sv) && (SvNV(sv) == 0.0 || SvNV(sv) == 1.0))
 		    useless = 0;
 		else if (SvPOK(sv)) {