diff --git a/compiler/mono/src/ir.rs b/compiler/mono/src/ir.rs
index 45ea50c6e5..ee6d8232ca 100644
--- a/compiler/mono/src/ir.rs
+++ b/compiler/mono/src/ir.rs
@@ -6556,11 +6556,15 @@ fn from_can_pattern_help<'a>(
                     let mut arguments = arguments.clone();
 
                     arguments.sort_by(|arg1, arg2| {
-                        let layout1 = layout_cache.from_var(env.arena, arg1.0, env.subs).unwrap();
-                        let layout2 = layout_cache.from_var(env.arena, arg2.0, env.subs).unwrap();
+                        let size1 = layout_cache
+                            .from_var(env.arena, arg1.0, env.subs)
+                            .map(|x| x.alignment_bytes(env.ptr_bytes))
+                            .unwrap_or(0);
 
-                        let size1 = layout1.alignment_bytes(env.ptr_bytes);
-                        let size2 = layout2.alignment_bytes(env.ptr_bytes);
+                        let size2 = layout_cache
+                            .from_var(env.arena, arg2.0, env.subs)
+                            .map(|x| x.alignment_bytes(env.ptr_bytes))
+                            .unwrap_or(0);
 
                         size2.cmp(&size1)
                     });
diff --git a/examples/benchmarks/RBTreeCk.roc b/examples/benchmarks/RBTreeCk.roc
index 2a1d3a03a1..4a69241984 100644
--- a/examples/benchmarks/RBTreeCk.roc
+++ b/examples/benchmarks/RBTreeCk.roc
@@ -60,7 +60,7 @@ main =
         Nil ->
             Task.putLine "fail"
 
-insert : Map, I64, Bool -> Map
+insert : Tree (Num k) v, (Num k), v -> Tree (Num k) v
 insert = \t, k, v -> if isRed t then setBlack (ins t k v) else ins t k v
 
 
@@ -78,7 +78,7 @@ isRed = \tree ->
 
 lt = \x, y -> x < y
 
-ins : Map, I64, Bool -> Map
+ins : Tree (Num k) v, (Num k), v -> Tree (Num k) v
 ins = \tree, kx, vx ->
     when tree is
         Leaf ->
@@ -100,7 +100,7 @@ ins = \tree, kx, vx ->
             else
                 Node Black a kx vx b
 
-balance1 : Map, Map -> Map 
+balance1 : Tree a b, Tree a b -> Tree a b 
 balance1 = \tree1, tree2 ->
     when tree1 is
         Leaf -> Leaf
@@ -111,7 +111,7 @@ balance1 = \tree1, tree2 ->
                 Node _ l  ky vy r                     -> Node Black (Node Red l ky vy r) kv vv t
                 Leaf -> Leaf
 
-balance2 : Map, Map -> Map 
+balance2 : Tree a b, Tree a b -> Tree a b 
 balance2 = \tree1, tree2 ->
     when tree1 is
         Leaf -> Leaf
diff --git a/examples/benchmarks/RBTreeDel.roc b/examples/benchmarks/RBTreeDel.roc
index 31cf63b2fa..172b97f7f2 100644
--- a/examples/benchmarks/RBTreeDel.roc
+++ b/examples/benchmarks/RBTreeDel.roc
@@ -87,7 +87,7 @@ isRed = \tree ->
 
 lt = \x, y -> x < y
 
-ins : Map, I64, Bool -> Map
+ins : Tree I64 Bool, I64, Bool -> Tree I64 Bool
 ins = \tree, kx, vx ->
     when tree is
         Leaf ->
@@ -188,11 +188,12 @@ delMin = \t ->
 
 
 
-delete : Map, I64 -> Map
+delete : Tree I64 Bool, I64 -> Tree I64 Bool
 delete = \t, k ->
     when del t k is
       Del tx _ -> setBlack tx
 
+del : Tree I64 Bool, I64 -> Del I64 Bool
 del = \t, k ->
     when t is
       Leaf -> Del Leaf False