diff --git a/src/sieve-tools/sieve-filter.c b/src/sieve-tools/sieve-filter.c
index 31c9f050f720e20310d13ebe37ad8d7b950ed6b1..9c5c9b7c2b6df195ceb564c8f81c78153da9ddab 100644
--- a/src/sieve-tools/sieve-filter.c
+++ b/src/sieve-tools/sieve-filter.c
@@ -311,7 +311,7 @@ static int filter_mailbox
 
 	/* Iterate through all requested messages */
 
-	while ( ret >= 0 && mailbox_search_next(search_ctx, &mail) > 0 ) {
+	while ( ret >= 0 && mailbox_search_next(search_ctx, &mail) ) {
 		ret = filter_message(&sfctx, mail);
 	}