diff --git a/vncviewer/PlatformPixelBuffer.cxx b/vncviewer/PlatformPixelBuffer.cxx
index 7b3f34a..a2b506d 100644
--- a/vncviewer/PlatformPixelBuffer.cxx
+++ b/vncviewer/PlatformPixelBuffer.cxx
@@ -154,7 +154,7 @@
 
   shminfo->shmid = shmget(IPC_PRIVATE,
                           xim->bytes_per_line * xim->height,
-                          IPC_CREAT|0777);
+                          IPC_CREAT|0600);
   if (shminfo->shmid == -1)
     goto free_xim;