diff --git a/ui-shared.c b/ui-shared.c
index 8a7cc32..d1b020b 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -466,7 +466,7 @@ void cgit_print_http_headers(struct cgit_context *ctx)
 	else if (ctx->page.mimetype)
 		htmlf("Content-Type: %s\n", ctx->page.mimetype);
 	if (ctx->page.size)
-		htmlf("Content-Length: %ld\n", ctx->page.size);
+		htmlf("Content-Length: %zd\n", ctx->page.size);
 	if (ctx->page.filename)
 		htmlf("Content-Disposition: inline; filename=\"%s\"\n",
 		      ctx->page.filename);