diff --git a/http.c b/http.c
index d59e59f66b..72973175a8 100644
--- a/http.c
+++ b/http.c
@@ -2290,17 +2290,19 @@ static int http_request_reauth(const char *url,
 		case HTTP_REQUEST_STRBUF:
 			strbuf_reset(result);
 			break;
-		case HTTP_REQUEST_FILE:
-			if (fflush(result)) {
+		case HTTP_REQUEST_FILE: {
+			FILE *f = result;
+			if (fflush(f)) {
 				error_errno("unable to flush a file");
 				return HTTP_START_FAILED;
 			}
-			rewind(result);
-			if (ftruncate(fileno(result), 0) < 0) {
+			rewind(f);
+			if (ftruncate(fileno(f), 0) < 0) {
 				error_errno("unable to truncate a file");
 				return HTTP_START_FAILED;
 			}
 			break;
+		}
 		default:
 			BUG("Unknown http_request target");
 		}