diff --git a/naga/src/back/glsl/mod.rs b/naga/src/back/glsl/mod.rs
index bede79610a..9ed7b6f1fa 100644
--- a/naga/src/back/glsl/mod.rs
+++ b/naga/src/back/glsl/mod.rs
@@ -3418,7 +3418,8 @@ impl<'a, W: Write> Writer<'a, W> {
                         let scalar_bits = ctx
                             .resolve_type(arg, &self.module.types)
                             .scalar_width()
-                            .unwrap();
+                            .unwrap()
+                            * 8;
 
                         write!(self.out, "bitfieldExtract(")?;
                         self.write_expr(arg, ctx)?;
@@ -3437,7 +3438,8 @@ impl<'a, W: Write> Writer<'a, W> {
                         let scalar_bits = ctx
                             .resolve_type(arg, &self.module.types)
                             .scalar_width()
-                            .unwrap();
+                            .unwrap()
+                            * 8;
 
                         write!(self.out, "bitfieldInsert(")?;
                         self.write_expr(arg, ctx)?;
diff --git a/naga/src/back/hlsl/writer.rs b/naga/src/back/hlsl/writer.rs
index d4c6097eb3..ccbb741c9b 100644
--- a/naga/src/back/hlsl/writer.rs
+++ b/naga/src/back/hlsl/writer.rs
@@ -2593,7 +2593,7 @@ impl<'a, W: fmt::Write> super::Writer<'a, W> {
                         true
                     }
                     None => {
-                        if inner.scalar_width() == Some(64) {
+                        if inner.scalar_width() == Some(8) {
                             false
                         } else {
                             write!(self.out, "{}(", kind.to_hlsl_cast(),)?;
diff --git a/naga/src/back/msl/writer.rs b/naga/src/back/msl/writer.rs
index 0d0f651665..7031d04361 100644
--- a/naga/src/back/msl/writer.rs
+++ b/naga/src/back/msl/writer.rs
@@ -1945,7 +1945,7 @@ impl<W: Write> Writer<W> {
                     //
                     // extract_bits(e, min(offset, w), min(count, w - min(offset, w))))
 
-                    let scalar_bits = context.resolve_type(arg).scalar_width().unwrap();
+                    let scalar_bits = context.resolve_type(arg).scalar_width().unwrap() * 8;
 
                     write!(self.out, "{NAMESPACE}::extract_bits(")?;
                     self.put_expression(arg, context, true)?;
@@ -1961,7 +1961,7 @@ impl<W: Write> Writer<W> {
                     //
                     // insertBits(e, newBits, min(offset, w), min(count, w - min(offset, w))))
 
-                    let scalar_bits = context.resolve_type(arg).scalar_width().unwrap();
+                    let scalar_bits = context.resolve_type(arg).scalar_width().unwrap() * 8;
 
                     write!(self.out, "{NAMESPACE}::insert_bits(")?;
                     self.put_expression(arg, context, true)?;
diff --git a/naga/src/back/spv/block.rs b/naga/src/back/spv/block.rs
index 9b8430e861..29116a4f83 100644
--- a/naga/src/back/spv/block.rs
+++ b/naga/src/back/spv/block.rs
@@ -1073,7 +1073,7 @@ impl<'w> BlockContext<'w> {
                         //
                         // bitfieldExtract(x, o, c)
 
-                        let bit_width = arg_ty.scalar_width().unwrap();
+                        let bit_width = arg_ty.scalar_width().unwrap() * 8;
                         let width_constant = self
                             .writer
                             .get_constant_scalar(crate::Literal::U32(bit_width as u32));
@@ -1129,7 +1129,7 @@ impl<'w> BlockContext<'w> {
                     Mf::InsertBits => {
                         // The behavior of InsertBits has the same undefined behavior as ExtractBits.
 
-                        let bit_width = arg_ty.scalar_width().unwrap();
+                        let bit_width = arg_ty.scalar_width().unwrap() * 8;
                         let width_constant = self
                             .writer
                             .get_constant_scalar(crate::Literal::U32(bit_width as u32));
@@ -1185,7 +1185,7 @@ impl<'w> BlockContext<'w> {
                     }
                     Mf::FindLsb => MathOp::Ext(spirv::GLOp::FindILsb),
                     Mf::FindMsb => {
-                        if arg_ty.scalar_width() == Some(32) {
+                        if arg_ty.scalar_width() == Some(4) {
                             let thing = match arg_scalar_kind {
                                 Some(crate::ScalarKind::Uint) => spirv::GLOp::FindUMsb,
                                 Some(crate::ScalarKind::Sint) => spirv::GLOp::FindSMsb,
diff --git a/naga/src/proc/mod.rs b/naga/src/proc/mod.rs
index 0e89f29032..0d45d8e47c 100644
--- a/naga/src/proc/mod.rs
+++ b/naga/src/proc/mod.rs
@@ -279,8 +279,9 @@ impl super::TypeInner {
         self.scalar().map(|scalar| scalar.kind)
     }
 
+    /// Returns the scalar width in bytes
     pub fn scalar_width(&self) -> Option<u8> {
-        self.scalar().map(|scalar| scalar.width * 8)
+        self.scalar().map(|scalar| scalar.width)
     }
 
     pub const fn pointer_space(&self) -> Option<crate::AddressSpace> {