diff --git a/benches/criterion.rs b/benches/criterion.rs
index ad00cb59e..624744555 100644
--- a/benches/criterion.rs
+++ b/benches/criterion.rs
@@ -149,7 +149,7 @@ fn backends(c: &mut Criterion) {
     let inputs = {
         let mut validator = naga::valid::Validator::new(
             naga::valid::ValidationFlags::empty(),
-            naga::valid::Capabilities::empty(),
+            naga::valid::Capabilities::default(),
         );
         let input_modules = gather_modules();
         input_modules
diff --git a/fuzz/fuzz_targets/ir.rs b/fuzz/fuzz_targets/ir.rs
index 86b7a6aa6..ae1d90747 100644
--- a/fuzz/fuzz_targets/ir.rs
+++ b/fuzz/fuzz_targets/ir.rs
@@ -5,6 +5,6 @@ fuzz_target!(|module: naga::Module| {
     use naga::valid as v;
     // Check if the module validates without errors.
     //TODO: may also fuzz the flags and capabilities
-    let mut validator = v::Validator::new(v::ValidationFlags::all(), v::Capabilities::empty());
+    let mut validator = v::Validator::new(v::ValidationFlags::all(), v::Capabilities::default());
     let _result = validator.validate(&module);
 });
diff --git a/src/valid/interface.rs b/src/valid/interface.rs
index 41f266612..7ba60515c 100644
--- a/src/valid/interface.rs
+++ b/src/valid/interface.rs
@@ -141,6 +141,7 @@ impl VaryingContext<'_> {
                     Bi::CullDistance => Capabilities::CULL_DISTANCE,
                     Bi::PrimitiveIndex => Capabilities::PRIMITIVE_INDEX,
                     Bi::ViewIndex => Capabilities::MULTIVIEW,
+                    Bi::SampleIndex => Capabilities::MULTISAMPLED_SHADING,
                     _ => Capabilities::empty(),
                 };
                 if !self.capabilities.contains(required) {
@@ -312,6 +313,14 @@ impl VaryingContext<'_> {
                 // qualifiers, so we won't complain about that here.
                 let _ = sampling;
 
+                let required = match sampling {
+                    Some(crate::Sampling::Sample) => Capabilities::MULTISAMPLED_SHADING,
+                    _ => Capabilities::empty(),
+                };
+                if !self.capabilities.contains(required) {
+                    return Err(VaryingError::UnsupportedCapability(required));
+                }
+
                 match ty_inner.scalar_kind() {
                     Some(crate::ScalarKind::Float) => {
                         if needs_interpolation && interpolation.is_none() {
diff --git a/src/valid/mod.rs b/src/valid/mod.rs
index ab4d81cb1..9d9c3f885 100644
--- a/src/valid/mod.rs
+++ b/src/valid/mod.rs
@@ -84,7 +84,6 @@ impl Default for ValidationFlags {
 bitflags::bitflags! {
     /// Allowed IR capabilities.
     #[must_use]
-    #[derive(Default)]
     #[cfg_attr(feature = "serialize", derive(serde::Serialize))]
     #[cfg_attr(feature = "deserialize", derive(serde::Deserialize))]
     pub struct Capabilities: u16 {
@@ -110,6 +109,14 @@ bitflags::bitflags! {
         const MULTIVIEW = 0x200;
         /// Support for `early_depth_test`.
         const EARLY_DEPTH_TEST = 0x400;
+        /// Support for [`Builtin::SampleIndex`] and [`Sampling::Sample`].
+        const MULTISAMPLED_SHADING = 0x800;
+    }
+}
+
+impl Default for Capabilities {
+    fn default() -> Self {
+        Self::MULTISAMPLED_SHADING
     }
 }
 
diff --git a/tests/snapshots.rs b/tests/snapshots.rs
index cc2b30055..7fea12200 100644
--- a/tests/snapshots.rs
+++ b/tests/snapshots.rs
@@ -98,7 +98,7 @@ fn check_targets(module: &naga::Module, name: &str, targets: Targets) {
     let capabilities = if params.god_mode {
         naga::valid::Capabilities::all()
     } else {
-        naga::valid::Capabilities::empty()
+        naga::valid::Capabilities::default()
     };
 
     let dest = PathBuf::from(root).join(BASE_DIR_OUT);
@@ -589,7 +589,7 @@ fn convert_spv(name: &str, adjust_coordinate_space: bool, targets: Targets) {
     check_targets(&module, name, targets);
     naga::valid::Validator::new(
         naga::valid::ValidationFlags::all(),
-        naga::valid::Capabilities::empty(),
+        naga::valid::Capabilities::default(),
     )
     .validate(&module)
     .unwrap();
diff --git a/tests/wgsl-errors.rs b/tests/wgsl-errors.rs
index f7c86b403..d76252ced 100644
--- a/tests/wgsl-errors.rs
+++ b/tests/wgsl-errors.rs
@@ -903,7 +903,7 @@ fn validation_error(source: &str) -> Result<naga::valid::ModuleInfo, naga::valid
     };
     naga::valid::Validator::new(
         naga::valid::ValidationFlags::all(),
-        naga::valid::Capabilities::empty(),
+        naga::valid::Capabilities::default(),
     )
     .validate(&module)
     .map_err(|e| e.into_inner()) // TODO: Add tests for spans, too?