diff --git a/mrbgems/stdlib-io.gembox b/mrbgems/stdlib-io.gembox
index cd1c2049c..0a9f6386f 100644
--- a/mrbgems/stdlib-io.gembox
+++ b/mrbgems/stdlib-io.gembox
@@ -9,4 +9,7 @@ MRuby::GemBox.new do |conf|
 
   # Use standard print/puts/p
   conf.gem :core => "mruby-print"
+
+  # Use errno extension for a good mruby-io/mruby-socket experience
+  conf.gem :core => "mruby-errno"
 end
diff --git a/mrbgems/stdlib.gembox b/mrbgems/stdlib.gembox
index 6b0452a6b..a4d01af1a 100644
--- a/mrbgems/stdlib.gembox
+++ b/mrbgems/stdlib.gembox
@@ -54,7 +54,4 @@ MRuby::GemBox.new do |conf|
 
   # Use class/module extension
   conf.gem :core => "mruby-class-ext"
-
-  # Use errno extension
-  conf.gem :core => "mruby-errno"
 end