diff --git a/test/configurable_test.rb b/test/configurable_test.rb
index c72b815..91e4e52 100644
--- a/test/configurable_test.rb
+++ b/test/configurable_test.rb
@@ -108,7 +108,7 @@ def test_config_guesses_integer_type_for_integer_default
     assert_equal 2, config.cast(2.1)
   
     err = assert_raises(ArgumentError) { config.cast('abc') }
-    assert_equal 'invalid value for Integer: "abc"', err.message
+    assert_match(/invalid value for Integer/, err.message)
   end
   
   class ConfigFloatTypeClass