diff --git a/scm-webapp/src/main/java/sonia/scm/filter/GZipResponseWrapper.java b/scm-webapp/src/main/java/sonia/scm/filter/GZipResponseWrapper.java
index f42d25ff17..8c1878a8c3 100644
--- a/scm-webapp/src/main/java/sonia/scm/filter/GZipResponseWrapper.java
+++ b/scm-webapp/src/main/java/sonia/scm/filter/GZipResponseWrapper.java
@@ -91,7 +91,10 @@ public class GZipResponseWrapper extends HttpServletResponseWrapper
   @Override
   public void flushBuffer() throws IOException
   {
-    stream.flush();
+    if (stream != null)
+    {
+      stream.flush();
+    }
   }
 
   //~--- get methods ----------------------------------------------------------