diff --git a/src/pattern.c b/src/pattern.c
index 135c0bcede89..93a956586b65 100644
--- a/src/pattern.c
+++ b/src/pattern.c
@@ -1793,8 +1793,10 @@ int pat_ref_set(struct pat_ref *ref, const char *key, const char *value, char **
 		elt = ebmb_entry(node, struct pat_ref_elt, node);
 		node = ebmb_next_dup(node);
 		if (!pat_ref_set_elt(ref, elt, value, &tmp_err)) {
-			memprintf(err, "%s, %s", err && *err ? *err : "", tmp_err);
-			ha_free(&tmp_err);
+			if (err)
+				*err = tmp_err;
+			else
+				ha_free(&tmp_err);
 			return 0;
 		}
 		found = 1;