diff --git a/src/Control/Monad/Effect/Fresh.hs b/src/Control/Monad/Effect/Fresh.hs
index 627f465e4..70733f3c0 100644
--- a/src/Control/Monad/Effect/Fresh.hs
+++ b/src/Control/Monad/Effect/Fresh.hs
@@ -15,6 +15,8 @@ data Fresh a where
 class Monad m => MonadFresh m where
   -- | Get a fresh variable name, guaranteed unused (since the last 'reset').
   fresh :: m TName
+
+  -- | Reset the sequence of variable names. Useful to avoid complicated alpha-equivalence comparisons when iteratively recomputing the results of an analysis til convergence.
   reset :: TName -> m ()
 
 instance (Fresh :< fs) => MonadFresh (Eff fs) where