diff --git a/diff.c b/diff.c
index 6fb97d462..144f2aaba 100644
--- a/diff.c
+++ b/diff.c
@@ -3853,6 +3853,13 @@ static int diff_get_patch_id(struct diff_options *options, unsigned char *sha1)
 					len2, p->two->path);
 		git_SHA1_Update(&ctx, buffer, len1);
 
+		if (diff_filespec_is_binary(p->one) ||
+		    diff_filespec_is_binary(p->two)) {
+			git_SHA1_Update(&ctx, sha1_to_hex(p->one->sha1), 40);
+			git_SHA1_Update(&ctx, sha1_to_hex(p->two->sha1), 40);
+			continue;
+		}
+
 		xpp.flags = 0;
 		xecfg.ctxlen = 3;
 		xecfg.flags = XDL_EMIT_FUNCNAMES;