diff --git a/dom/system/OSFileConstants.cpp b/dom/system/OSFileConstants.cpp
index 99cc11e05c86..d78f2a94bc01 100644
--- a/dom/system/OSFileConstants.cpp
+++ b/dom/system/OSFileConstants.cpp
@@ -63,7 +63,6 @@
 #include "nsServiceManagerUtils.h"
 #include "nsString.h"
 #include "nsSystemInfo.h"
-#include "nsAutoPtr.h"
 #include "nsDirectoryServiceDefs.h"
 #include "nsXULAppAPI.h"
 #include "nsAppDirectoryServiceDefs.h"
@@ -71,6 +70,7 @@
 
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/StaticPtr.h"
+#include "mozilla/UniquePtr.h"
 
 #include "OSFileConstants.h"
 #include "nsIOSFileConstantsService.h"
@@ -243,7 +243,7 @@ OSFileConstantsService::InitOSFileConstants()
     return NS_OK;
   }
 
-  nsAutoPtr<Paths> paths(new Paths);
+  UniquePtr<Paths> paths(new Paths);
 
   // Initialize paths->libDir
   nsCOMPtr<nsIFile> file;
diff --git a/dom/system/OSFileConstants.h b/dom/system/OSFileConstants.h
index 1573976030e2..09e9406eb7ec 100644
--- a/dom/system/OSFileConstants.h
+++ b/dom/system/OSFileConstants.h
@@ -44,7 +44,7 @@ private:
   bool mInitialized;
 
   struct Paths;
-  nsAutoPtr<Paths> mPaths;
+  UniquePtr<Paths> mPaths;
 
   /**
    * (Unix) the umask, which goes in OS.Constants.Sys but