diff --git a/crates/fayalite-proc-macros-impl/src/hdl_bundle.rs b/crates/fayalite-proc-macros-impl/src/hdl_bundle.rs
index eefa8be..79326e2 100644
--- a/crates/fayalite-proc-macros-impl/src/hdl_bundle.rs
+++ b/crates/fayalite-proc-macros-impl/src/hdl_bundle.rs
@@ -340,7 +340,7 @@ impl ToTokens for Builder {
                 }));
             quote_spanned! {self.ident.span()=>
                 #[automatically_derived]
-                #[allow(non_camel_case_types, dead_code)]
+                #[allow(non_camel_case_types, non_snake_case, dead_code)]
                 impl #impl_generics #unfilled_ty
                 #where_clause
                 {
diff --git a/crates/fayalite/tests/hdl_types.rs b/crates/fayalite/tests/hdl_types.rs
index bd7c0fd..bed1a82 100644
--- a/crates/fayalite/tests/hdl_types.rs
+++ b/crates/fayalite/tests/hdl_types.rs
@@ -9,8 +9,7 @@ pub struct S<T, Len: Size, T2> {
     b: UInt<3>,
     pub(crate) c: ArrayType<UInt<1>, Len>,
     pub d: T2,
-    pub e: PhantomData<T>,
-    pub f: PhantomData<Len>,
+    pub _phantom: PhantomData<(T, Len)>,
 }
 
 #[hdl(outline_generated)]