2 files changed, 10 insertions, 1 deletions
diff --git a/activemodel/lib/active_model/errors.rb b/activemodel/lib/active_model/errors.rb
index 191039f598..72746e194e 100644
--- a/activemodel/lib/active_model/errors.rb
+++ b/activemodel/lib/active_model/errors.rb
@@ -280,7 +280,7 @@ module ActiveModel
           messages[attribute] = array.map { |message| full_message(attribute, message) }
         end
       else
-        messages.dup
+        without_default_proc(messages)
       end
     end
 
diff --git a/activemodel/lib/active_model/type/float.rb b/activemodel/lib/active_model/type/float.rb
index 94bb7e700c..4d0d2771a0 100644
--- a/activemodel/lib/active_model/type/float.rb
+++ b/activemodel/lib/active_model/type/float.rb
@@ -7,6 +7,15 @@ module ActiveModel
         :float
       end
 
+      def type_cast_for_schema(value)
+        return "::Float::NAN" if value.try(:nan?)
+        case value
+        when ::Float::INFINITY then "::Float::INFINITY"
+        when -::Float::INFINITY then "-::Float::INFINITY"
+        else super
+        end
+      end
+
       alias serialize cast
 
       private