diff --git a/lib/postal/message_db/delivery.rb b/lib/postal/message_db/delivery.rb
index 5b8fe0c..1fbeb48 100644
--- a/lib/postal/message_db/delivery.rb
+++ b/lib/postal/message_db/delivery.rb
@@ -20,13 +20,13 @@ module Postal
       end
 
       def method_missing(name, value = nil, &block)
-        return unless @attributes.has_key?(name.to_s)
+        return unless @attributes.key?(name.to_s)
 
         @attributes[name.to_s]
       end
 
       def respond_to_missing?(name)
-        @attributes.has_key?(name.to_s)
+        @attributes.key?(name.to_s)
       end
 
       def timestamp
diff --git a/lib/postal/message_db/message.rb b/lib/postal/message_db/message.rb
index 7b1bff3..7222640 100644
--- a/lib/postal/message_db/message.rb
+++ b/lib/postal/message_db/message.rb
@@ -178,7 +178,7 @@ module Postal
       #  Provide access to set and get acceptable attributes
       #
       def method_missing(name, value = nil, &block)
-        if @attributes.has_key?(name.to_s)
+        if @attributes.key?(name.to_s)
           @attributes[name.to_s]
         elsif name.to_s =~ /=\z/
           @attributes[name.to_s.gsub("=", "").to_s] = value
@@ -187,7 +187,7 @@ module Postal
 
       def respond_to_missing?(name)
         name = name.to_s.sub(/=\z/, "")
-        @attributes.has_key?(name.to_s)
+        @attributes.key?(name.to_s)
       end
 
       #