diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb
index 694ff85fa132c4dae007d14c5e84e166f8a77e80..9b985e049b245735a772133779cf280d130b81e5 100644
--- a/activerecord/lib/active_record/model_schema.rb
+++ b/activerecord/lib/active_record/model_schema.rb
@@ -375,7 +375,7 @@ def type_for_attribute(attr_name, &block)
       # default values when instantiating the Active Record object for this table.
       def column_defaults
         load_schema
-        @column_defaults ||= _default_attributes.to_hash
+        @column_defaults ||= _default_attributes.deep_dup.to_hash
       end
 
       def _default_attributes # :nodoc:
diff --git a/activerecord/test/cases/attributes_test.rb b/activerecord/test/cases/attributes_test.rb
index 3bc56694beede84f8950a4710ac2c1b594252da9..2632aec7abccd2a7cca8fd0018dde137a5af332f 100644
--- a/activerecord/test/cases/attributes_test.rb
+++ b/activerecord/test/cases/attributes_test.rb
@@ -148,6 +148,20 @@ def deserialize(*)
       assert_equal 2, klass.new.counter
     end
 
+    test "procs for default values are evaluated even after column_defaults is called" do
+      klass = Class.new(OverloadedType) do
+        @@counter = 0
+        attribute :counter, :integer, default: -> { @@counter += 1 }
+      end
+
+      assert_equal 1, klass.new.counter
+
+      # column_defaults will increment the counter since the proc is called
+      klass.column_defaults
+
+      assert_equal 3, klass.new.counter
+    end
+
     test "procs are memoized before type casting" do
       klass = Class.new(OverloadedType) do
         @@counter = 0