diff --git a/lib/isc/quota.c b/lib/isc/quota.c
index 137838828f..2f69e86feb 100644
--- a/lib/isc/quota.c
+++ b/lib/isc/quota.c
@@ -119,6 +119,8 @@ quota_release(isc_quota_t *quota) {
 		UNLOCK(&quota->cblock);
 		if (cb != NULL) {
 			cb->cb_func(quota, cb->data);
+			cb->cb_func = NULL;
+			cb->data = NULL;
 			return;
 		}
 	}