diff --git a/fast-import.c b/fast-import.c
index 4d55910ab9..12195d54d7 100644
--- a/fast-import.c
+++ b/fast-import.c
@@ -1076,7 +1076,7 @@ static int store_object(
 		return 1;
 	}
 
-	if (last && last->data.buf && last->depth < max_depth
+	if (last && last->data.len && last->data.buf && last->depth < max_depth
 		&& dat->len > the_hash_algo->rawsz) {
 
 		delta_count_attempts_by_type[type]++;