diff --git a/ChangeLog b/ChangeLog
index 9cefa5d11f..a470d687f1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Thu May 14 00:39:29 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* dln.c (dln_load): check if a different libruby is loaded by the
+	  extension library, and then bail out to get rid of very frequent
+	  reported stale bug reports.
+
 Thu May 14 00:29:44 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* lib/fileutils.rb (FileUtils#mv): show the exact target path in
diff --git a/dln.c b/dln.c
index 355cec1090..e5269ca441 100644
--- a/dln.c
+++ b/dln.c
@@ -106,13 +106,12 @@ dln_loaderror(const char *format, ...)
 # define USE_DLN_DLOPEN
 #endif
 
-#ifndef FUNCNAME_PATTERN
-# if defined(__hp9000s300) || ((defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)) && !defined(__ELF__)) || defined(__BORLANDC__) || defined(NeXT) || defined(__WATCOMC__) || defined(MACOSX_DYLD)
-#  define FUNCNAME_PREFIX "_Init_"
-# else
-#  define FUNCNAME_PREFIX "Init_"
-# endif
+#if defined(__hp9000s300) || ((defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)) && !defined(__ELF__)) || defined(__BORLANDC__) || defined(NeXT) || defined(__WATCOMC__) || defined(MACOSX_DYLD)
+# define EXTERNAL_PREFIX "_"
+#else
+# define EXTERNAL_PREFIX ""
 #endif
+#define FUNCNAME_PREFIX EXTERNAL_PREFIX"Init_"
 
 #if defined __CYGWIN__ || defined DOSISH
 #define isdirsep(x) ((x) == '/' || (x) == '\\')
@@ -1330,6 +1329,23 @@ dln_load(const char *file)
 	    error = dln_strerror();
 	    goto failed;
 	}
+# if defined RUBY_EXPORT
+	{
+	    static const char incompatible[] = "incompatible library version";
+	    void *ex = dlsym(handle, EXTERNAL_PREFIX"ruby_xmalloc");
+	    if (ex && ex != ruby_xmalloc) {
+
+#   if defined __APPLE__
+		/* dlclose() segfaults */
+		rb_fatal("%s - %s", incompatible, file);
+#   else
+		dlclose(handle);
+		error = incompatible;
+		goto failed;
+#   endif
+	    }
+	}
+# endif
 
 	init_fct = (void(*)())(VALUE)dlsym(handle, buf);
 	if (init_fct == NULL) {
diff --git a/version.h b/version.h
index d9b49e8d5a..208d5ca9d9 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.2.3"
 #define RUBY_RELEASE_DATE "2015-05-14"
-#define RUBY_PATCHLEVEL 99
+#define RUBY_PATCHLEVEL 100
 
 #define RUBY_RELEASE_YEAR 2015
 #define RUBY_RELEASE_MONTH 5