diff --git a/nac3core/src/codegen/expr.rs b/nac3core/src/codegen/expr.rs
index 66232d89..de9c9f71 100644
--- a/nac3core/src/codegen/expr.rs
+++ b/nac3core/src/codegen/expr.rs
@@ -201,7 +201,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
     /// See [`get_llvm_type`].
     pub fn get_llvm_type<G: CodeGenerator + ?Sized>(
         &mut self,
-        generator: &mut G,
+        generator: &G,
         ty: Type,
     ) -> BasicTypeEnum<'ctx> {
         get_llvm_type(
@@ -218,7 +218,7 @@ impl<'ctx, 'a> CodeGenContext<'ctx, 'a> {
     /// See [`get_llvm_abi_type`].
     pub fn get_llvm_abi_type<G: CodeGenerator + ?Sized>(
         &mut self,
-        generator: &mut G,
+        generator: &G,
         ty: Type,
     ) -> BasicTypeEnum<'ctx> {
         get_llvm_abi_type(
diff --git a/nac3core/src/codegen/mod.rs b/nac3core/src/codegen/mod.rs
index 2f4a9ec5..2619f5e1 100644
--- a/nac3core/src/codegen/mod.rs
+++ b/nac3core/src/codegen/mod.rs
@@ -444,7 +444,7 @@ pub struct CodeGenTask {
 fn get_llvm_type<'ctx, G: CodeGenerator + ?Sized>(
     ctx: &'ctx Context,
     module: &Module<'ctx>,
-    generator: &mut G,
+    generator: &G,
     unifier: &mut Unifier,
     top_level: &TopLevelContext,
     type_cache: &mut HashMap<Type, BasicTypeEnum<'ctx>>,
@@ -569,7 +569,7 @@ fn get_llvm_type<'ctx, G: CodeGenerator + ?Sized>(
 fn get_llvm_abi_type<'ctx, G: CodeGenerator + ?Sized>(
     ctx: &'ctx Context,
     module: &Module<'ctx>,
-    generator: &mut G,
+    generator: &G,
     unifier: &mut Unifier,
     top_level: &TopLevelContext,
     type_cache: &mut HashMap<Type, BasicTypeEnum<'ctx>>,