diff --git a/lib/i18n/tasks/concurrent/cached_value.rb b/lib/i18n/tasks/concurrent/cached_value.rb
index a9e93ec1..bafe65bc 100644
--- a/lib/i18n/tasks/concurrent/cached_value.rb
+++ b/lib/i18n/tasks/concurrent/cached_value.rb
@@ -13,6 +13,11 @@ class CachedValue
     def initialize(&computation)
       @computation = computation
       @mutex = Mutex.new
+
+      # Ruby instance variables are currently implicitly "volatile" in all major implementations, see:
+      # https://bugs.ruby-lang.org/issues/11539
+      #
+      # If the Ruby specification changes, this variable must be marked "volatile".
       @result = NULL
     end