diff --git a/rubygem-method_source.spec b/rubygem-method_source.spec
index 2f40f8d..df80a2f 100644
--- a/rubygem-method_source.spec
+++ b/rubygem-method_source.spec
@@ -6,6 +6,8 @@ Release:             1
 License:             MIT
 URL:                 https://banisterfiend.wordpress.com
 Source0:             http://rubygems.org/gems/%{gem_name}-%{version}.gem
+# Fix Fixnum/Bignum deprecated warning for Ruby 2.4.0.
+# https://github.com/banister/method_source/commit/05ce7fc
 Patch0:              rubygem-method_source-0.8.2-fix-fixnum-bignum-warnings.patch
 Patch1:              rubygem-method_source-0.8.2-fix-fixnum-bignum-warnings-tests.patch
 BuildRequires:       ruby(release) rubygems-devel ruby rubygem-bacon