diff --git a/branch.c b/branch.c
index 46fb34554f..427bde896f 100644
--- a/branch.c
+++ b/branch.c
@@ -37,7 +37,7 @@ static int find_tracked_branch(struct remote *remote, void *priv)
 	if (!remote_find_tracking(remote, &tracking->spec)) {
 		switch (++tracking->matches) {
 		case 1:
-			string_list_append(tracking->srcs, tracking->spec.src);
+			string_list_append_nodup(tracking->srcs, tracking->spec.src);
 			tracking->remote = remote->name;
 			break;
 		case 2: