diff --git a/crates/fayalite/src/intern.rs b/crates/fayalite/src/intern.rs
index b68140b..4969bcb 100644
--- a/crates/fayalite/src/intern.rs
+++ b/crates/fayalite/src/intern.rs
@@ -605,7 +605,14 @@ pub struct Interner<T: ?Sized + 'static + Send + Sync> {
 impl<T: ?Sized + 'static + Send + Sync> Interner<T> {
     fn get() -> &'static Interner<T> {
         static TYPE_ID_MAP: TypeIdMap = TypeIdMap::new();
-        TYPE_ID_MAP.get_or_insert_default()
+        thread_local! {
+            static TYPE_ID_MAP_CACHE: TypeIdMap = const { TypeIdMap::new() };
+        }
+        TYPE_ID_MAP_CACHE.with(|cache| {
+            cache.get_or_insert_with(|| {
+                TYPE_ID_MAP.get_or_insert_with(|| Box::leak(Default::default()))
+            })
+        })
     }
 }
 
@@ -1035,10 +1042,17 @@ pub trait MemoizeGeneric: 'static + Send + Sync + Hash + Eq + Copy {
     fn inner(self, input: Self::InputRef<'_>) -> Self::Output;
     fn get_cow(self, input: Self::InputCow<'_>) -> Self::Output {
         static TYPE_ID_MAP: TypeIdMap = TypeIdMap::new();
+        thread_local! {
+            static TYPE_ID_MAP_CACHE: TypeIdMap = const { TypeIdMap::new() };
+        }
         let map: &RwLock<(
             DefaultBuildHasher,
             HashTable<(Self, Self::InputOwned, Self::Output)>,
-        )> = TYPE_ID_MAP.get_or_insert_default();
+        )> = TYPE_ID_MAP_CACHE.with(|cache| {
+            cache.get_or_insert_with(|| {
+                TYPE_ID_MAP.get_or_insert_with(|| Box::leak(Default::default()))
+            })
+        });
         fn hash_eq_key<'a, 'b, T: MemoizeGeneric>(
             this: &'a T,
             input: T::InputRef<'b>,
diff --git a/crates/fayalite/src/intern/type_map.rs b/crates/fayalite/src/intern/type_map.rs
index 945116b..03b68e3 100644
--- a/crates/fayalite/src/intern/type_map.rs
+++ b/crates/fayalite/src/intern/type_map.rs
@@ -87,20 +87,23 @@ impl TypeIdMap {
     fn insert_slow(
         &self,
         type_id: TypeId,
-        make: fn() -> Box<dyn Any + Sync + Send>,
+        make: impl FnOnce() -> &'static (dyn Any + Sync + Send),
     ) -> &'static (dyn Any + Sync + Send) {
-        let value = Box::leak(make());
+        let value = make();
         let mut write_guard = self.0.write().unwrap();
         *write_guard.entry(type_id).or_insert(value)
     }
-    pub(crate) fn get_or_insert_default<T: Sized + Any + Send + Sync + Default>(&self) -> &T {
+    pub(crate) fn get_or_insert_with<T: Sized + Any + Send + Sync>(
+        &self,
+        make: impl FnOnce() -> &'static T,
+    ) -> &'static T {
         let type_id = TypeId::of::<T>();
         let read_guard = self.0.read().unwrap();
         let retval = read_guard.get(&type_id).map(|v| *v);
         drop(read_guard);
         let retval = match retval {
             Some(retval) => retval,
-            None => self.insert_slow(type_id, move || Box::new(T::default())),
+            None => self.insert_slow(type_id, move || make()),
         };
         retval.downcast_ref().expect("known to have correct TypeId")
     }