diff --git a/src/runtime/haskell/PGF/Data.hs b/src/runtime/haskell/PGF/Data.hs
index a3d7c1f93..426936cba 100644
--- a/src/runtime/haskell/PGF/Data.hs
+++ b/src/runtime/haskell/PGF/Data.hs
@@ -79,7 +79,7 @@ type Sequence = Array DotPos Symbol
 type FunId = Int
 type SeqId = Int
 
--- merge two PGFs; fails is differens absnames; priority to second arg
+-- merge two PGFs; fails if different abstract names; priority to second arg
 
 unionPGF :: PGF -> PGF -> PGF
 unionPGF one two = fst $ msgUnionPGF one two