diff --git a/code/__HELPERS/lists.dm b/code/__HELPERS/lists.dm
index 58a87f374a7..afc07638e4b 100644
--- a/code/__HELPERS/lists.dm
+++ b/code/__HELPERS/lists.dm
@@ -55,7 +55,7 @@
 /proc/is_type_in_list(atom/A, list/L)
 	if (!L.len)
 		return 0
-	if (!isnum(L[L[1]]))
+	if (!L[L[1]])
 		generate_type_list_cache(L)
 	return L[A.type]