diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 1adab2e832..502fe0442e 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -1648,34 +1648,10 @@ module ActiveRecord #:nodoc:
         # single-table inheritance model that makes it possible to create
         # objects of different types from the same table.
         def instantiate(record)
-          object =
-            if subclass_name = record[inheritance_column]
-              # No type given.
-              if subclass_name.empty?
-                allocate
+          object = find_sti_class(record[inheritance_column]).allocate
 
-              # Ignore type if no column is present since it was probably
-              # pulled in from a sloppy join.
-              elsif !columns_hash.include?(inheritance_column)
-                allocate
-
-              else
-                begin
-                  compute_type(subclass_name).allocate
-                rescue NameError
-                  raise SubclassNotFound,
-                    "The single-table inheritance mechanism failed to locate the subclass: '#{record[inheritance_column]}'. " +
-                    "This error is raised because the column '#{inheritance_column}' is reserved for storing the class in case of inheritance. " +
-                    "Please rename this column if you didn't intend it to be used for storing the inheritance class " +
-                    "or overwrite #{self.to_s}.inheritance_column to use another column for that information."
-                end
-              end
-            else
-              allocate
-            end
-
-          object.instance_variable_set("@attributes", record)
-          object.instance_variable_set("@attributes_cache", Hash.new)
+          object.instance_variable_set(:'@attributes', record)
+          object.instance_variable_set(:'@attributes_cache', {})
 
           object.send(:_run_find_callbacks)
           object.send(:_run_initialize_callbacks)
@@ -1683,6 +1659,22 @@ module ActiveRecord #:nodoc:
           object
         end
 
+        def find_sti_class(type_name)
+          if type_name.blank? || !columns_hash.include?(inheritance_column)
+            self
+          else
+            begin
+              compute_type(type_name)
+            rescue NameError
+              raise SubclassNotFound,
+                "The single-table inheritance mechanism failed to locate the subclass: '#{type_name}'. " +
+                "This error is raised because the column '#{inheritance_column}' is reserved for storing the class in case of inheritance. " +
+                "Please rename this column if you didn't intend it to be used for storing the inheritance class " +
+                "or overwrite #{name}.inheritance_column to use another column for that information."
+            end
+          end
+        end
+
         # Nest the type name in the same module as this class.
         # Bar is "MyApp::Business::Bar" relative to MyApp::Business::Foo
         def type_name_with_module(type_name)