diff --git a/mfbt/fallible.h b/mfbt/fallible.h
index 649f4b1863c5..fabb54e82a7e 100644
--- a/mfbt/fallible.h
+++ b/mfbt/fallible.h
@@ -24,7 +24,7 @@
  *
  *     foo = new ((mozilla::fallible_t())) Foo();
  *
- *     const mozilla::fallible_t fallible = mozilla::fallible_t();
+ *     const mozilla::fallible_t f = mozilla::fallible_t();
  *     bar = new (f) Bar();
  *
  * It is also possible to declare method overloads with fallible allocation