diff --git a/fcore/search-list/dfa-gen.sml b/fcore/search-list/dfa-gen.sml
index 57fd337..d41ed18 100644
--- a/fcore/search-list/dfa-gen.sml
+++ b/fcore/search-list/dfa-gen.sml
@@ -274,7 +274,7 @@ struct
             in lastpos (r, acc)
             end
           else
-            lastpos (l, acc)
+            lastpos (r, acc)
       | ALTERNATION {l, r, ...} =>
           let val acc = lastpos (l, acc)
           in lastpos (r, acc)