diff --git a/findnonce.c b/findnonce.c
index 344c7d15..2bfc1ef8 100644
--- a/findnonce.c
+++ b/findnonce.c
@@ -254,7 +254,14 @@ static void *postcalc_hash(void *userdata)
 
 	/* To prevent corrupt values in FOUND from trying to read beyond the
 	 * end of the res[] array */
-	pcd->res[FOUND] &= FOUND;
+	if (unlikely(pcd->res[FOUND] & ~FOUND)) {
+		applog(LOG_WARNING, "%s%d: invalid nonce count - HW error",
+				thr->cgpu->api->name, thr->cgpu->device_id);
+		hw_errors++;
+		thr->cgpu->hw_errors++;
+		pcd->res[FOUND] &= FOUND;
+	}
+
 	for (entry = 0; entry < pcd->res[FOUND]; entry++) {
 		uint32_t nonce = pcd->res[entry];