1 files changed, 1 insertions, 3 deletions
diff --git a/src/main/java/org/shedlang/compiler/types/TypeSubstitution.java b/src/main/java/org/shedlang/compiler/types/TypeSubstitution.java
index cc7ddbc9..4b29895c 100644
--- a/src/main/java/org/shedlang/compiler/types/TypeSubstitution.java
+++ b/src/main/java/org/shedlang/compiler/types/TypeSubstitution.java
@@ -1,7 +1,6 @@
 package org.shedlang.compiler.types;
 
 import java.util.List;
-import java.util.Optional;
 import java.util.function.BiFunction;
 
 public class TypeSubstitution {
@@ -107,8 +106,7 @@ public class TypeSubstitution {
         TypeSubstitutionMap map
     ) {
         return new FunctionType(
-            // TODO: don't clear type level params
-            Optional.empty(),
+            functionType.typeLevelParams(),
             functionType.positionalParams().stream()
                 .map(param -> substituteType(param, map))
                 .toList(),