diff --git a/ChangeLog b/ChangeLog
index a70f41dc76..16d1d221b0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Fri Mar  2 16:35:56 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* io.c (pipe_open): cmd is no longer used if fork is available.
+
 Thu Mar  1 16:13:18 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* internal.h (rb_file_const, rb_file_load_ok): moved functions for
diff --git a/io.c b/io.c
index 5d49f7f9f0..35104c6f4c 100644
--- a/io.c
+++ b/io.c
@@ -5430,14 +5430,14 @@ pipe_open(struct rb_exec_arg *eargp, VALUE prog, const char *modestr, int fmode,
     FILE *fp = 0;
     int fd = -1;
     int write_fd = -1;
-    const char *cmd = 0;
 #if !defined(HAVE_FORK)
+    const char *cmd = 0;
     int argc;
     VALUE *argv;
-#endif
 
     if (prog)
         cmd = StringValueCStr(prog);
+#endif
 
 #if !defined(HAVE_FORK)
     if (!eargp) {