diff --git a/buffet/commands/command_definition.h b/buffet/commands/command_definition.h
index 3328a94..a5e2916 100644
--- a/buffet/commands/command_definition.h
+++ b/buffet/commands/command_definition.h
@@ -19,7 +19,7 @@
 // constraints. See comments for CommandDefinitions::LoadCommands for the
 // detailed description of what command categories are and what they are used
 // for.
-class CommandDefinition {
+class CommandDefinition final {
  public:
   struct Visibility {
     Visibility() = default;