diff --git a/src/encoder.rs b/src/encoder.rs
index fa2873a..34a755b 100644
--- a/src/encoder.rs
+++ b/src/encoder.rs
@@ -131,7 +131,7 @@ pub struct MTLScissorRect {
 
 unsafe impl Encode for MTLScissorRect {
     const ENCODING: Encoding = Encoding::Struct(
-        "MTLScissorRect",
+        "?",
         &[
             NSUInteger::ENCODING,
             NSUInteger::ENCODING,
@@ -155,7 +155,7 @@ pub struct MTLViewport {
 
 unsafe impl Encode for MTLViewport {
     const ENCODING: Encoding = Encoding::Struct(
-        "MTLViewport",
+        "?",
         &[
             f64::ENCODING,
             f64::ENCODING,
@@ -198,7 +198,7 @@ pub struct VertexAmplificationViewMapping {
 
 unsafe impl Encode for VertexAmplificationViewMapping {
     const ENCODING: Encoding = Encoding::Struct(
-        "VertexAmplificationViewMapping",
+        "?",
         &[u32::ENCODING, u32::ENCODING],
     );
 }
diff --git a/src/renderpass.rs b/src/renderpass.rs
index 78267b1..5ac0995 100644
--- a/src/renderpass.rs
+++ b/src/renderpass.rs
@@ -48,7 +48,7 @@ pub struct MTLClearColor {
 
 unsafe impl Encode for MTLClearColor {
     const ENCODING: Encoding = Encoding::Struct(
-        "MTLClearColor",
+        "?",
         &[f64::ENCODING, f64::ENCODING, f64::ENCODING, f64::ENCODING],
     );
 }
diff --git a/src/resource.rs b/src/resource.rs
index 72119fd..d3c6c2b 100644
--- a/src/resource.rs
+++ b/src/resource.rs
@@ -130,7 +130,7 @@ pub struct MTLSizeAndAlign {
 
 unsafe impl Encode for MTLSizeAndAlign {
     const ENCODING: Encoding = Encoding::Struct(
-        "MTLSizeAndAlign",
+        "?",
         &[NSUInteger::ENCODING, NSUInteger::ENCODING],
     );
 }
diff --git a/src/types.rs b/src/types.rs
index 3cc29f9..0e961a5 100644
--- a/src/types.rs
+++ b/src/types.rs
@@ -68,7 +68,7 @@ pub struct MTLRegion {
 
 unsafe impl Encode for MTLRegion {
     const ENCODING: Encoding =
-        Encoding::Struct("MTLRegion", &[MTLOrigin::ENCODING, MTLSize::ENCODING]);
+        Encoding::Struct("?", &[MTLOrigin::ENCODING, MTLSize::ENCODING]);
 }
 
 impl MTLRegion {
@@ -112,7 +112,7 @@ pub struct MTLSamplePosition {
 
 unsafe impl Encode for MTLSamplePosition {
     const ENCODING: Encoding =
-        Encoding::Struct("MTLSamplePosition", &[f32::ENCODING, f32::ENCODING]);
+        Encoding::Struct("?", &[f32::ENCODING, f32::ENCODING]);
 }
 
 #[repr(C)]