diff --git a/ChangeLog b/ChangeLog
index b01741f293..d22d422a6c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,7 @@
-Thu Apr 14 21:20:51 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Thu Apr 14 21:21:01 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* include/ruby/win32.h (ftruncate, truncate): mingw64 misses
+	  prototypes.
 
 	* win32/win32.c (rb_w32_read): suppress warning.
 
diff --git a/include/ruby/win32.h b/include/ruby/win32.h
index f9dadb222e..cafd7de85f 100644
--- a/include/ruby/win32.h
+++ b/include/ruby/win32.h
@@ -384,13 +384,13 @@ scalb(double a, long b)
 
 #if !defined HAVE_FTRUNCATE || defined(_MSC_VER)
 #define ftruncate rb_w32_ftruncate
-extern int       rb_w32_ftruncate(int fd, off_t length);
 #endif
+extern int       ftruncate(int fd, off_t length);
 
 #if !defined HAVE_TRUNCATE || defined(_MSC_VER)
 #define truncate rb_w32_truncate
-extern int       rb_w32_truncate(const char *path, off_t length);
 #endif
+extern int       truncate(const char *path, off_t length);
 
 extern int       fseeko(FILE *stream, off_t offset, int whence);