diff --git a/lib/imgbundler/imgbundler_test.go b/lib/imgbundler/imgbundler_test.go
index 89fa61cba..d40753f08 100644
--- a/lib/imgbundler/imgbundler_test.go
+++ b/lib/imgbundler/imgbundler_test.go
@@ -121,7 +121,7 @@ width="328" height="587" viewBox="-100 -131 328 587"><style type="text/css">
 	// Test almost too large response
 	transport = roundTripFunc(func(req *http.Request) *http.Response {
 		respRecorder := httptest.NewRecorder()
-		bytes := make([]byte, maxImageSize-1)
+		bytes := make([]byte, maxImageSize)
 		rand.Read(bytes)
 		respRecorder.Write(bytes)
 		respRecorder.WriteHeader(200)