diff --git a/src/eval.c b/src/eval.c
index b7003a8..2100d80 100644
--- a/src/eval.c
+++ b/src/eval.c
@@ -1449,7 +1449,7 @@
 		else
 		{
 		    // Need a real list here.
-		    range_list_materialize(l);
+		    CHECK_LIST_MATERIALIZE(l);
 
 		    // No need to increment the refcount, it's already set for
 		    // the list being used in "tv".