diff --git a/activemodel/lib/active_model/callbacks.rb b/activemodel/lib/active_model/callbacks.rb
index b27a39b787..467028f9e8 100644
--- a/activemodel/lib/active_model/callbacks.rb
+++ b/activemodel/lib/active_model/callbacks.rb
@@ -97,6 +97,9 @@ module ActiveModel
     #       # obj is the MyModel instance that the callback is being called on
     #     end
     #   end
+    #
+    # NOTE: +method_name+ passed to `define_model_callbacks` must not end with
+    # `!`, `?` and `=`.
     def define_model_callbacks(*callbacks)
       options = callbacks.extract_options!
       options = {
diff --git a/activesupport/lib/active_support/callbacks.rb b/activesupport/lib/active_support/callbacks.rb
index 0c8c1d7dfb..21a2f54bc1 100644
--- a/activesupport/lib/active_support/callbacks.rb
+++ b/activesupport/lib/active_support/callbacks.rb
@@ -719,6 +719,9 @@ module ActiveSupport
       #     define_callbacks :save, scope: [:name]
       #
       #   would call <tt>Audit#save</tt>.
+      #
+      # NOTE: +method_name+ passed to `define_model_callbacks` must not end with
+      # `!`, `?` and `=`.
       def define_callbacks(*names)
         options = names.extract_options!