diff --git a/editor/src/lang/ast.rs b/editor/src/lang/ast.rs
index f95266fb79..80557ea41e 100644
--- a/editor/src/lang/ast.rs
+++ b/editor/src/lang/ast.rs
@@ -270,17 +270,17 @@ impl ShallowClone for ValueDef {
 #[derive(Debug)]
 pub enum FunctionDef {
     WithAnnotation {
-        name: Symbol,                          // 8B
-        arguments: PoolVec<(Pattern2, Type2)>, // 8B
-        rigids: NodeId<Rigids>,                // 4B
-        return_type: TypeId,                   // 4B
-        body: ExprId,                          // 4B
+        name: Symbol,                           // 8B
+        arguments: PoolVec<(PatternId, Type2)>, // 8B
+        rigids: NodeId<Rigids>,                 // 4B
+        return_type: TypeId,                    // 4B
+        body: ExprId,                           // 4B
     },
     NoAnnotation {
-        name: Symbol,                             // 8B
-        arguments: PoolVec<(Pattern2, Variable)>, // 8B
-        return_var: Variable,                     // 4B
-        body: ExprId,                             // 4B
+        name: Symbol,                              // 8B
+        arguments: PoolVec<(PatternId, Variable)>, // 8B
+        return_var: Variable,                      // 4B
+        body: ExprId,                              // 4B
     },
 }
 
diff --git a/editor/src/lang/def.rs b/editor/src/lang/def.rs
index 0cd3b25ba0..c179145a7c 100644
--- a/editor/src/lang/def.rs
+++ b/editor/src/lang/def.rs
@@ -514,7 +514,7 @@ fn canonicalize_pending_def<'a>(
                             // parent commit for the bug this fixed!
                             let refs = References::new();
 
-                            let arguments: PoolVec<(Pattern2, Type2)> =
+                            let arguments: PoolVec<(PatternId, Type2)> =
                                 PoolVec::with_capacity(closure_args.len() as u32, env.pool);
 
                             let return_type: TypeId;
@@ -551,9 +551,7 @@ fn canonicalize_pending_def<'a>(
                                     for (node_id, ((_, pattern_id), typ)) in
                                         arguments.iter_node_ids().zip(it.into_iter())
                                     {
-                                        let pattern = &env.pool[pattern_id];
-
-                                        env.pool[node_id] = (pattern.shallow_clone(), typ);
+                                        env.pool[node_id] = (pattern_id, typ);
                                     }
 
                                     return_type = return_type_id;
@@ -683,16 +681,14 @@ fn canonicalize_pending_def<'a>(
                     // parent commit for the bug this fixed!
                     let refs = References::new();
 
-                    let arguments: PoolVec<(Pattern2, Variable)> =
+                    let arguments: PoolVec<(PatternId, Variable)> =
                         PoolVec::with_capacity(closure_args.len() as u32, env.pool);
 
                     let it: Vec<_> = closure_args.iter(env.pool).map(|(x, y)| (*x, *y)).collect();
 
                     for (node_id, (_, pattern_id)) in arguments.iter_node_ids().zip(it.into_iter())
                     {
-                        let pattern = &env.pool[pattern_id];
-
-                        env.pool[node_id] = (pattern.shallow_clone(), env.var_store.fresh());
+                        env.pool[node_id] = (pattern_id, env.var_store.fresh());
                     }
 
                     let function_def = FunctionDef::NoAnnotation {
diff --git a/editor/src/lang/pool.rs b/editor/src/lang/pool.rs
index e68199e339..a35a7f63f0 100644
--- a/editor/src/lang/pool.rs
+++ b/editor/src/lang/pool.rs
@@ -13,6 +13,7 @@
 use libc::{c_void, MAP_ANONYMOUS, MAP_PRIVATE, PROT_READ, PROT_WRITE};
 use roc_can::expected::Expected;
 use roc_can::expected::PExpected;
+use std::any::type_name;
 use std::cmp::Ordering;
 use std::marker::PhantomData;
 use std::mem::size_of;
@@ -322,7 +323,12 @@ impl<'a, T: 'a + Sized> PoolVec<T> {
     }
 
     pub fn with_capacity(len: u32, pool: &mut Pool) -> Self {
-        debug_assert!(size_of::<T>() <= NODE_BYTES, "{}", size_of::<T>());
+        debug_assert!(
+            size_of::<T>() <= NODE_BYTES,
+            "{} has a size of {}",
+            type_name::<T>(),
+            size_of::<T>()
+        );
 
         if len == 0 {
             Self::empty(pool)