diff --git a/merge-recursive.c b/merge-recursive.c
index 2be1e17e08..1f86338ad3 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -1888,8 +1888,8 @@ int merge_trees(struct merge_options *o,
 	else
 		clean = 1;
 
-	if (o->call_depth)
-		*result = write_tree_from_memory(o);
+	if (o->call_depth && !(*result = write_tree_from_memory(o)))
+		return -1;
 
 	return clean;
 }