diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
index fe47f2e08f3dc..44243ed50e61e 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/quoting.rb
@@ -149,6 +149,7 @@ def type_cast(value) # :nodoc:
         end
 
         def lookup_cast_type_from_column(column) # :nodoc:
+          verify! if type_map.nil?
           type_map.lookup(column.oid, column.fmod, column.sql_type)
         end
 
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
index 005047f167ff5..1ebd03f115f62 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql_adapter.rb
@@ -716,9 +716,7 @@ def initialize_type_map(m) # :nodoc:
       end
 
       private
-        def type_map
-          @type_map ||= Type::HashLookupTypeMap.new
-        end
+        attr_reader :type_map
 
         def initialize_type_map(m = type_map)
           self.class.initialize_type_map(m)