diff --git a/xpcom/base/nsStackWalk.cpp b/xpcom/base/nsStackWalk.cpp
index a091af95e6cb..bac8fc27cabb 100644
--- a/xpcom/base/nsStackWalk.cpp
+++ b/xpcom/base/nsStackWalk.cpp
@@ -1031,7 +1031,7 @@ NS_DescribeCodeAddress(void *aPC, nsCodeAddressDetails *aDetails)
         // This just makes sure we get good info if available.
         //
 
-        DWORD addr = (DWORD)aPC;
+        DWORD_PTR addr = (DWORD_PTR)aPC;
         IMAGEHLP_MODULE modInfo;
         IMAGEHLP_LINE lineInfo;
         BOOL modInfoRes;
diff --git a/xpcom/ds/nsWindowsRegKey.cpp b/xpcom/ds/nsWindowsRegKey.cpp
index 8e7cc1df4e30..0fa484f006cf 100644
--- a/xpcom/ds/nsWindowsRegKey.cpp
+++ b/xpcom/ds/nsWindowsRegKey.cpp
@@ -139,7 +139,7 @@ nsWindowsRegKey::OpenChild(const nsAString &path, PRUint32 mode,
   if (!child)
     return NS_ERROR_OUT_OF_MEMORY;
   
-  nsresult rv = child->Open((PRUint32) mKey, path, mode);
+  nsresult rv = child->Open((uintptr_t) mKey, path, mode);
   if (NS_FAILED(rv))
     return rv;
 
@@ -157,7 +157,7 @@ nsWindowsRegKey::CreateChild(const nsAString &path, PRUint32 mode,
   if (!child)
     return NS_ERROR_OUT_OF_MEMORY;
   
-  nsresult rv = child->Create((PRUint32) mKey, path, mode);
+  nsresult rv = child->Create((uintptr_t) mKey, path, mode);
   if (NS_FAILED(rv))
     return rv;