diff --git a/mozilla/widget/src/windows/nsDataObj.cpp b/mozilla/widget/src/windows/nsDataObj.cpp
index 003f2f5d16f..78615ff0356 100644
--- a/mozilla/widget/src/windows/nsDataObj.cpp
+++ b/mozilla/widget/src/windows/nsDataObj.cpp
@@ -528,9 +528,9 @@ MangleTextToValidFilename(nsString & aText)
 
   aText.StripChars(FILE_PATH_SEPARATOR  FILE_ILLEGAL_CHARACTERS);
   aText.CompressWhitespace(PR_TRUE, PR_TRUE);
-  int nameLen;
-  for (int n = 0; n < NS_ARRAY_LENGTH(forbiddenNames); ++n) {
-    nameLen = strlen(forbiddenNames[n]);
+  PRUint32 nameLen;
+  for (size_t n = 0; n < NS_ARRAY_LENGTH(forbiddenNames); ++n) {
+    nameLen = (PRUint32) strlen(forbiddenNames[n]);
     if (aText.EqualsIgnoreCase(forbiddenNames[n], nameLen)) {
       // invalid name is either the entire string, or a prefix with a period
       if (aText.Length() == nameLen || aText.CharAt(nameLen) == PRUnichar('.')) {
diff --git a/mozilla/widget/src/windows/nsDataObj.h b/mozilla/widget/src/windows/nsDataObj.h
index c48fcef470d..5808cc9f18e 100644
--- a/mozilla/widget/src/windows/nsDataObj.h
+++ b/mozilla/widget/src/windows/nsDataObj.h
@@ -63,6 +63,46 @@
 #define CFSTR_INETURLW    "UniformResourceLocatorW"
 #endif
 
+// For support of MinGW w32api v2.4. 
+// When the next version of w32api is released with shlobj.h rev 1.35 
+// http://sources.redhat.com/cgi-bin/cvsweb.cgi/src/winsup/w32api/include/shlobj.h?cvsroot=src
+// then that can be made the base required version and this code should be removed.
+#ifndef CFSTR_FILEDESCRIPTORA
+# define CFSTR_FILEDESCRIPTORA   "FileGroupDescriptor"
+#endif
+#ifndef CFSTR_FILEDESCRIPTORW
+# define CFSTR_FILEDESCRIPTORW   "FileGroupDescriptorW"
+#endif
+
+#ifdef __MINGW32__
+# include <w32api.h>
+# if __W32API_MAJOR_VERSION < 3 || (__W32API_MAJOR_VERSION == 3 && __W32API_MINOR_VERSION == 0)
+#  ifndef FILEGROUPDESCRIPTORA
+#   define FILEGROUPDESCRIPTORA    FILEGROUPDESCRIPTOR
+#  endif
+#  ifndef LPFILEGROUPDESCRIPTORA
+#   define LPFILEGROUPDESCRIPTORA  LPFILEGROUPDESCRIPTOR
+#  endif
+typedef struct _FILEDESCRIPTORW {
+   DWORD dwFlags;
+   CLSID clsid;
+   SIZEL sizel;
+   POINTL pointl;
+   DWORD dwFileAttributes;
+   FILETIME ftCreationTime;
+   FILETIME ftLastAccessTime;
+   FILETIME ftLastWriteTime;
+   DWORD nFileSizeHigh;
+   DWORD nFileSizeLow;
+   WCHAR cFileName[MAX_PATH];
+} FILEDESCRIPTORW,*LPFILEDESCRIPTORW;
+typedef struct _FILEGROUPDESCRIPTORW {
+   UINT cItems;
+   FILEDESCRIPTORW fgd[1];
+} FILEGROUPDESCRIPTORW,*LPFILEGROUPDESCRIPTORW;
+# endif /*__W32API_MAJOR_VERSION*/
+#endif /*__MINGW32__*/
+
 class nsVoidArray;
 class CEnumFormatEtc;
 class nsITransferable;