diff --git a/sdk/lib/atl/atlsimpstr.h b/sdk/lib/atl/atlsimpstr.h
index 2b571a299e0..ce0286602b4 100644
--- a/sdk/lib/atl/atlsimpstr.h
+++ b/sdk/lib/atl/atlsimpstr.h
@@ -373,6 +373,11 @@ public:
         return m_pszData;
     }
 
+    void Preallocate(_In_ int nLength)
+    {
+        PrepareWrite(nLength);
+    }
+
     void ReleaseBufferSetLength(_In_ int nNewLength)
     {
         ATLASSERT(nNewLength >= 0);