diff --git a/src/Assigning/Assignment/Deterministic.hs b/src/Assigning/Assignment/Deterministic.hs
index 1a41c1f2c..903113401 100644
--- a/src/Assigning/Assignment/Deterministic.hs
+++ b/src/Assigning/Assignment/Deterministic.hs
@@ -117,7 +117,7 @@ instance (Enum symbol, Ord symbol, Show symbol) => Assigning symbol (Assignment
       NotNullable -> NotNullable)
     (firstSet a)
     (map (fmap (\ match src state follow -> case match src state follow of
-      Left err -> Left err
+      Left err -> Right (advanceState state, termIn (stateLocation state) (inject (Syntax.errorSyntax (either id show <$> err) [])))
       Right (state', syntax) -> Right (state', termIn (stateLocation state) (inject syntax)))) (choices a))