diff --git a/lib/net/imap.rb b/lib/net/imap.rb
index 84bc0946..5cc11478 100644
--- a/lib/net/imap.rb
+++ b/lib/net/imap.rb
@@ -761,7 +761,7 @@ module Net
   # * {IMAP URLAUTH Authorization Mechanism Registry}[https://www.iana.org/assignments/urlauth-authorization-mechanism-registry/urlauth-authorization-mechanism-registry.xhtml]
   #
   class IMAP < Protocol
-    VERSION = "0.4.21"
+    VERSION = "0.4.22"
 
     # Aliases for supported capabilities, to be used with the #enable command.
     ENABLE_ALIASES = {
diff --git a/lib/net/imap/config/attr_type_coercion.rb b/lib/net/imap/config/attr_type_coercion.rb
index e0db0784..0941d1b7 100644
--- a/lib/net/imap/config/attr_type_coercion.rb
+++ b/lib/net/imap/config/attr_type_coercion.rb
@@ -28,11 +28,8 @@ def self.included(mod)
         end
         private_class_method :included
 
-        if defined?(Ractor.make_shareable)
-          def self.safe(...) Ractor.make_shareable nil.instance_eval(...).freeze end
-        else
-          def self.safe(...) nil.instance_eval(...).freeze end
-        end
+        # Used in v0.5.8+ for Ractor sharability.
+        def self.safe(...) nil.instance_eval(...).freeze end
         private_class_method :safe
 
         Types = Hash.new do |h, type|