diff --git a/extensions/cookie/nsPermissionManager.cpp b/extensions/cookie/nsPermissionManager.cpp
index 2878e8c63bb9..aeffea017027 100644
--- a/extensions/cookie/nsPermissionManager.cpp
+++ b/extensions/cookie/nsPermissionManager.cpp
@@ -861,7 +861,10 @@ nsPermissionManager::Write()
   }
 
   nsCOMPtr<nsIOutputStream> fileOutputStream;
-  rv = NS_NewSafeLocalFileOutputStream(getter_AddRefs(fileOutputStream), mPermissionsFile);
+  rv = NS_NewSafeLocalFileOutputStream(getter_AddRefs(fileOutputStream),
+                                       mPermissionsFile,
+                                       -1,
+                                       0600);
   NS_ENSURE_SUCCESS(rv, rv);
 
   // get a buffered output stream 4096 bytes big, to optimize writes
diff --git a/netwerk/cookie/src/nsCookieService.cpp b/netwerk/cookie/src/nsCookieService.cpp
index 3d4001a09088..577ca83b3104 100644
--- a/netwerk/cookie/src/nsCookieService.cpp
+++ b/netwerk/cookie/src/nsCookieService.cpp
@@ -1036,7 +1036,10 @@ nsCookieService::Write()
 
   nsresult rv;
   nsCOMPtr<nsIOutputStream> fileOutputStream;
-  rv = NS_NewSafeLocalFileOutputStream(getter_AddRefs(fileOutputStream), mCookieFile);
+  rv = NS_NewSafeLocalFileOutputStream(getter_AddRefs(fileOutputStream),
+                                       mCookieFile,
+                                       -1,
+                                       0600);
   if (NS_FAILED(rv)) {
     NS_ERROR("failed to open cookies.txt for writing");
     return rv;