diff --git a/ChangeLog b/ChangeLog
index c6fd8f654d..54d3037b58 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat Feb  1 06:30:20 2014  Zachary Scott  <e@zzak.io>
+
+	* error.c: [DOC] Document Exception#cause by @jasonrclark [ci skip]
+	  [Fixes GH-519] https://github.com/ruby/ruby/pull/519
+
 Sat Feb  1 06:10:49 2014  Zachary Scott  <e@zzak.io>
 
 	* lib/securerandom.rb: [DOC] Add note on require for examples
diff --git a/error.c b/error.c
index b9d8d52809..773d679e23 100644
--- a/error.c
+++ b/error.c
@@ -804,6 +804,15 @@ rb_exc_set_backtrace(VALUE exc, VALUE bt)
     return exc_set_backtrace(exc, bt);
 }
 
+/*
+ * call-seq:
+ *   exception.cause   -> an_exception
+ *
+ * Returns the previous exception ($!) at the time this exception was raised.
+ * This is useful for wrapping exceptions and retaining the original exception
+ * information.
+ */
+
 VALUE
 exc_cause(VALUE exc)
 {