diff --git a/naga/src/proc/builtins.rs b/naga/src/proc/builtins.rs
index fe1c1c449a7..ea625f74019 100644
--- a/naga/src/proc/builtins.rs
+++ b/naga/src/proc/builtins.rs
@@ -298,7 +298,7 @@ macro_rules! where_clause {
 
 /// Nicer notation for [`TypeSet`] values.
 macro_rules! typeset {
-    ( ( vecN or scalar < $scalar:ident > ) ) => (
+    ( ( vecN or scalar < $scalar:tt > ) ) => (
         TypeSet {
             constructors: ConstructorSet::VECN.union(ConstructorSet::SCALAR),
             scalars: scalar!($scalar),
@@ -310,7 +310,7 @@ macro_rules! typeset {
             scalars: scalar!($scalar),
         }
     );
-    ( $scalar:ident ) => (
+    ( $scalar:tt ) => (
         TypeSet {
             constructors: ConstructorSet::SCALAR,
             scalars: scalar!($scalar),
@@ -322,11 +322,14 @@ macro_rules! typeset {
 macro_rules! scalar {
     ( numeric ) => ( ScalarSet::NUMERIC );
     ( float ) => ( ScalarSet::ANY_FLOAT );
+    ( ( concrete integer ) ) => ( ScalarSet::CONCRETE_INTEGER );
+    ( u32 ) => ( ScalarSet::UINT_32 );
 }
 
 /// Nicer notation for [`ReturnType`] values.
 macro_rules! return_type {
     ( T ) => { ReturnType::Match(0) };
+    ( S ) => { ReturnType::Match(1) };
     ( ( scalar T ) ) => { ReturnType::MatchScalar(0) };
 }
 
@@ -378,6 +381,7 @@ impl crate::MathFunction {
             Mf::Atan2 => b!((T, T) -> T where (T: (vecN or scalar<float>))),
 
             Mf::Dot => b!((T, T) -> (scalar T) where (T: (vecN<numeric>))),
+            Mf::InsertBits => b!((T, T, S, S) -> S where (T: (vecN or scalar<(concrete integer)>), S: u32)),
 /*
             // Functions of three floating-point arguments, extended
             // element-wise to vectors.
@@ -426,7 +430,6 @@ impl crate::MathFunction {
             Mf::FaceForward => todo!(),
             Mf::Fma => todo!(),
             Mf::Frexp => todo!(),
-            Mf::InsertBits => todo!(),
             Mf::Inverse => todo!(),
             Mf::Ldexp => todo!(),
             Mf::Mix => todo!(),