diff --git a/crates/interpreter/src/types.rs b/crates/interpreter/src/types.rs
index 45e1ca07..28d1fb73 100644
--- a/crates/interpreter/src/types.rs
+++ b/crates/interpreter/src/types.rs
@@ -17,14 +17,13 @@ pub fn size_of_ty_data(ctx: &ModuleCtx, ty: Type) -> usize {
         Type::I256 => 32,
         Type::Compound(cmpd_ty) => {
             use CompoundTypeData::*;
-            let cmpd_ty_data = ctx.with_ty_store(|s| s.resolve_compound(cmpd_ty).clone());
-            match cmpd_ty_data {
-                Array { len, elem } => len * size_of_ty_data(ctx, elem),
+            ctx.with_ty_store(|s| match s.resolve_compound(cmpd_ty) {
+                Array { len, elem } => len * size_of_ty_data(ctx, *elem),
                 Ptr(_) => mem::size_of::<usize>(),
                 Struct(data) => data.fields.iter().fold(0usize, |acc, field_ty| {
                     acc + size_of_ty_data(ctx, *field_ty)
                 }),
-            }
+            })
         }
         Type::Void => mem::size_of::<()>(),
     }
diff --git a/crates/ir/src/module.rs b/crates/ir/src/module.rs
index 5e68d721..4813086f 100644
--- a/crates/ir/src/module.rs
+++ b/crates/ir/src/module.rs
@@ -1,6 +1,6 @@
 use std::{
     fmt,
-    sync::{Arc, Mutex},
+    sync::{Arc, RwLock},
 };
 
 use cranelift_entity::{entity_impl, PrimaryMap};
@@ -43,17 +43,17 @@ impl Module {
 pub struct ModuleCtx {
     pub isa: TargetIsa,
     // TODO: Consider using `RwLock` instead of `Mutex`.
-    type_store: Arc<Mutex<TypeStore>>,
+    type_store: Arc<RwLock<TypeStore>>,
     // TODO: Consider using `RwLock` instead of `Mutex`.
-    gv_store: Arc<Mutex<GlobalVariableStore>>,
+    gv_store: Arc<RwLock<GlobalVariableStore>>,
 }
 
 impl ModuleCtx {
     pub fn new(isa: TargetIsa) -> Self {
         Self {
             isa,
-            type_store: Arc::new(Mutex::new(TypeStore::default())),
-            gv_store: Arc::new(Mutex::new(GlobalVariableStore::default())),
+            type_store: Arc::new(RwLock::new(TypeStore::default())),
+            gv_store: Arc::new(RwLock::new(GlobalVariableStore::default())),
         }
     }
 
@@ -61,28 +61,28 @@ impl ModuleCtx {
     where
         F: FnOnce(&TypeStore) -> R,
     {
-        f(&self.type_store.lock().unwrap())
+        f(&self.type_store.read().unwrap())
     }
 
     pub fn with_ty_store_mut<F, R>(&self, f: F) -> R
     where
         F: FnOnce(&mut TypeStore) -> R,
     {
-        f(&mut self.type_store.lock().unwrap())
+        f(&mut self.type_store.write().unwrap())
     }
 
     pub fn with_gv_store<F, R>(&self, f: F) -> R
     where
         F: FnOnce(&GlobalVariableStore) -> R,
     {
-        f(&self.gv_store.lock().unwrap())
+        f(&self.gv_store.read().unwrap())
     }
 
     pub fn with_gv_store_mut<F, R>(&self, f: F) -> R
     where
         F: FnOnce(&mut GlobalVariableStore) -> R,
     {
-        f(&mut self.gv_store.lock().unwrap())
+        f(&mut self.gv_store.write().unwrap())
     }
 }