diff --git a/ChangeLog b/ChangeLog
index b78b0dcf2e..bbf0672740 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Mon Aug  2 21:51:16 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ruby.c (ruby_init_loadpath_safe): rb_str_set_len modifies ptr
+	  since r26303.
+
 Mon Aug  2 21:16:03 2010  Masaki Suketa <masaki.suketa@nifty.ne.jp>
 
 	* ext/win32ole/win32ole.c: NONAMELESSUNION defined only if gcc
diff --git a/ruby.c b/ruby.c
index 1a445ea6cd..5196b0faf0 100644
--- a/ruby.c
+++ b/ruby.c
@@ -422,13 +422,15 @@ ruby_init_loadpath_safe(int safe_level)
 	strlcpy(libpath, ".", sizeof(libpath));
 	p = libpath + 1;
     }
+    baselen = p - libpath;
 #define PREFIX_PATH() rb_str_new(libpath, baselen)
 #else
-    rb_str_set_len(sopath, p - libpath);
+    baselen = p - libpath;
+    rb_str_set_len(sopath, baselen);
+    libpath = RSTRING_PTR(sopath);
 #define PREFIX_PATH() sopath
 #endif
 
-    baselen = p - libpath;
 #define BASEPATH() rb_str_buf_cat(rb_str_buf_new(baselen+len), libpath, baselen)
 
 #define RUBY_RELATIVE(path, len) rb_str_buf_cat(BASEPATH(), path, len)