1 files changed, 1 insertions, 1 deletions

diff --git a/shared.c b/shared.c
index c7cd8a5..f20fb5c 100644
--- a/shared.c
+++ b/shared.c
@@ -360,7 +360,7 @@ void cgit_diff_tree(const unsigned char *old_sha1,
         opt.format_callback_data = fn;
         diff_setup_done(&opt);
 
-        if (old_sha1)
+        if (old_sha1 && !is_null_sha1(old_sha1))
                 ret = diff_tree_sha1(old_sha1, new_sha1, "", &opt);
         else
                 ret = diff_root_tree_sha1(new_sha1, "", &opt);