diff --git a/lib/isc/iterated_hash.c b/lib/isc/iterated_hash.c
index 80d219c56b..ad623814e6 100644
--- a/lib/isc/iterated_hash.c
+++ b/lib/isc/iterated_hash.c
@@ -44,18 +44,22 @@ isc_iterated_hash(unsigned char *out, const unsigned int hashalg,
 
 	do {
 		if (SHA1_Init(&ctx) != 1) {
+			ERR_clear_error();
 			return (0);
 		}
 
 		if (SHA1_Update(&ctx, buf, len) != 1) {
+			ERR_clear_error();
 			return (0);
 		}
 
 		if (SHA1_Update(&ctx, salt, saltlength) != 1) {
+			ERR_clear_error();
 			return (0);
 		}
 
 		if (SHA1_Final(out, &ctx) != 1) {
+			ERR_clear_error();
 			return (0);
 		}