Index: source/i18n/winnmfmt.cpp
===================================================================
--- source/i18n/winnmfmt.cpp	(revision 287122)
+++ source/i18n/winnmfmt.cpp	(working copy)
@@ -242,7 +242,7 @@
     NumberFormat::setMinimumFractionDigits(newValue);
 }
 
-UnicodeString &Win32NumberFormat::format(int32_t numDigits, UnicodeString &appendTo, wchar_t *fmt, ...) const
+UnicodeString &Win32NumberFormat::format(int32_t numDigits, UnicodeString &appendTo, const wchar_t *fmt, ...) const
 {
     wchar_t nStackBuffer[STACK_BUFFER_SIZE];
     wchar_t *nBuffer = nStackBuffer;
Index: source/i18n/winnmfmt.h
===================================================================
--- source/i18n/winnmfmt.h	(revision 287122)
+++ source/i18n/winnmfmt.h	(working copy)
@@ -143,7 +143,7 @@
     virtual UClassID getDynamicClassID(void) const;
 
 private:
-    UnicodeString &format(int32_t numDigits, UnicodeString &appendTo, wchar_t *format, ...) const;
+    UnicodeString &format(int32_t numDigits, UnicodeString &appendTo, const wchar_t *format, ...) const;
 
     UBool fCurrency;
     Locale fLocale;