diff --git a/ChangeLog b/ChangeLog
index 855a3854ae..fe6ae86e3c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+Wed Sep  9 16:55:45 2015  NAKAMURA Usaku  <usa@ruby-lang.org>
+
+	* ruby.c (usage, enable_option, disable_option, process_options): new
+	  option `--disable_did_you_mean`.
+
+	* gem_prelude.rb: now requires did_you_mean gem by default if available.
+
 Wed Sep  9 13:38:56 2015  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* tool/extlibs.rb (do_patch): let "patch" command change the
diff --git a/gem_prelude.rb b/gem_prelude.rb
index 3d4516f341..3f171d1145 100644
--- a/gem_prelude.rb
+++ b/gem_prelude.rb
@@ -1 +1,7 @@
-require 'rubygems.rb' if defined?(Gem)
+if defined?(Gem)
+  require 'rubygems.rb'
+  begin
+    require 'did_you_mean'
+  rescue LoadError
+  end if defined?(DidYouMean)
+end
diff --git a/ruby.c b/ruby.c
index a6f5ca1e0e..389aac522c 100644
--- a/ruby.c
+++ b/ruby.c
@@ -62,6 +62,7 @@ char *getenv();
 #define DISABLE_BIT(bit) (1U << disable_##bit)
 enum disable_flag_bits {
     disable_gems,
+    disable_did_you_mean,
     disable_rubyopt,
     disable_flag_count
 };
@@ -192,6 +193,7 @@ usage(const char *name, int help)
     };
     static const struct message features[] = {
 	M("gems",    "",        "rubygems (default: "DEFAULT_RUBYGEMS_ENABLED")"),
+	M("did_you_mean", "",   "did_you_mean (default: "DEFAULT_RUBYGEMS_ENABLED")"),
 	M("rubyopt", "",        "RUBYOPT environment variable (default: enabled)"),
     };
     int i;
@@ -710,6 +712,7 @@ enable_option(const char *str, int len, void *arg)
 {
 #define UNSET_WHEN_DISABLE(bit) UNSET_WHEN(#bit, DISABLE_BIT(bit), str, len)
     UNSET_WHEN_DISABLE(gems);
+    UNSET_WHEN_DISABLE(did_you_mean);
     UNSET_WHEN_DISABLE(rubyopt);
     if (NAME_MATCH_P("all", str, len)) {
 	*(unsigned int *)arg = 0U;
@@ -723,6 +726,7 @@ disable_option(const char *str, int len, void *arg)
 {
 #define SET_WHEN_DISABLE(bit) SET_WHEN(#bit, DISABLE_BIT(bit), str, len)
     SET_WHEN_DISABLE(gems);
+    SET_WHEN_DISABLE(did_you_mean);
     SET_WHEN_DISABLE(rubyopt);
     if (NAME_MATCH_P("all", str, len)) {
 	*(unsigned int *)arg = ~0U;
@@ -1435,6 +1439,9 @@ process_options(int argc, char **argv, struct cmdline_options *opt)
     if (!(opt->disable & DISABLE_BIT(gems))) {
 	rb_define_module("Gem");
     }
+    if (!(opt->disable & DISABLE_BIT(did_you_mean))) {
+	rb_define_module("DidYouMean");
+    }
     ruby_init_prelude();
 #if UTF8_PATH
     opt->script_name = str_conv_enc(opt->script_name, rb_utf8_encoding(), lenc);