diff --git a/src/kiss/Kiss.hx b/src/kiss/Kiss.hx
index b96ed37..afaf020 100644
--- a/src/kiss/Kiss.hx
+++ b/src/kiss/Kiss.hx
@@ -70,7 +70,7 @@ class Kiss {
                 "symbol" => Symbol("Prelude.symbol"),
                 "expList" => Symbol("Prelude.expList"),
                 "map" => Symbol("Lambda.map"),
-                "filter" => Symbol("Lambda.filter"), // TODO use truthy as the default filter function
+                "filter" => Symbol("Prelude.filter"),
                 "flatten" => Symbol("Lambda.flatten"),
                 "has" => Symbol("Lambda.has"),
                 "count" => Symbol("Lambda.count"),
diff --git a/src/kiss/Prelude.hx b/src/kiss/Prelude.hx
index d67e214..009905a 100644
--- a/src/kiss/Prelude.hx
+++ b/src/kiss/Prelude.hx
@@ -517,4 +517,10 @@ class Prelude {
         throw "Can't run a subprocess on this target.";
         #end
     }
+
+    public static function filter<T>(l:Iterable<T>, ?p:(T) -> Bool):kiss.List<T> {
+        if (p == null)
+            p = Prelude.truthy;
+        return Lambda.filter(l, p);
+    }
 }