diff --git a/winsup/w32api/ChangeLog b/winsup/w32api/ChangeLog
index 50e91c962..334448698 100644
--- a/winsup/w32api/ChangeLog
+++ b/winsup/w32api/ChangeLog
@@ -1,3 +1,9 @@
+2009-20-10  Chris Sutcliffe  <ir0nh34d@users.sourceforge.net>
+
+	* include/winbase.h (UnmapViewOfFile): Correct definition.
+
+	Thanks to Dimitry Sibiryakov for the report.
+
 2009-20-10  Aleksey Chernov  <virxkane@users.sourceforge.net>
 
 	* include/sspi.h: Include ntsecapi.h to correct postgresql build error.
diff --git a/winsup/w32api/include/winbase.h b/winsup/w32api/include/winbase.h
index 3e3eee19e..2e634fc95 100644
--- a/winsup/w32api/include/winbase.h
+++ b/winsup/w32api/include/winbase.h
@@ -2013,7 +2013,7 @@ WINBASEAPI BOOL WINAPI UnlockFile(HANDLE,DWORD,DWORD,DWORD,DWORD);
 WINBASEAPI BOOL WINAPI UnlockFileEx(HANDLE,DWORD,DWORD,DWORD,LPOVERLAPPED);
 #define UnlockResource(h) (h)
 #define UnlockSegment(w) GlobalUnfix((HANDLE)(w)) /* Obsolete: Has no effect. */
-WINBASEAPI BOOL WINAPI UnmapViewOfFile(PVOID);
+WINBASEAPI BOOL WINAPI UnmapViewOfFile(LPCVOID);
 #if (_WIN32_WINNT >= 0x0500)
 WINBASEAPI BOOL WINAPI UnregisterWait(HANDLE);
 WINBASEAPI BOOL WINAPI UnregisterWaitEx(HANDLE,HANDLE);