Index: shlwapi/path.c
===================================================================
--- shlwapi/path.c	(revision 47213)
+++ shlwapi/path.c	(working copy)
@@ -2532,9 +2532,9 @@
  *  FALSE If lpszPath or lpszExtension are invalid, lpszPath has an
  *        extension already, or the new path length is too big.
  *
- * FIXME
- *  What version of shlwapi.dll adds "exe" if lpszExtension is NULL? Win2k
- *  does not do this, so the behaviour was removed.
+ * NOTE
+ *  PathAddExtension on WinXP SP3 and WinMe add ".exe" to lpszPath
+ *  if lpszExtension == NULL. Win2k is old.
  */
 BOOL WINAPI PathAddExtensionA(LPSTR lpszPath, LPCSTR lpszExtension)
 {
@@ -2542,9 +2542,12 @@
 
   TRACE("(%s,%s)\n", debugstr_a(lpszPath), debugstr_a(lpszExtension));
 
-  if (!lpszPath || !lpszExtension || *(PathFindExtensionA(lpszPath)))
+  if (!lpszPath || *(PathFindExtensionA(lpszPath)))
     return FALSE;
 
+  if (!lpszExtension)
+    lpszExtension = ".exe";
+
   dwLen = strlen(lpszPath);
 
   if (dwLen + strlen(lpszExtension) >= MAX_PATH)
@@ -2565,9 +2568,12 @@
 
   TRACE("(%s,%s)\n", debugstr_w(lpszPath), debugstr_w(lpszExtension));
 
-  if (!lpszPath || !lpszExtension || *(PathFindExtensionW(lpszPath)))
+  if (!lpszPath || *(PathFindExtensionW(lpszPath)))
     return FALSE;
 
+  if (!lpszExtension)
+    lpszExtension = L".exe";
+
   dwLen = strlenW(lpszPath);
 
   if (dwLen + strlenW(lpszExtension) >= MAX_PATH)