diff --git a/internal/shaderir/glsl/type.go b/internal/shaderir/glsl/type.go
index 2888a9768..387e82705 100644
--- a/internal/shaderir/glsl/type.go
+++ b/internal/shaderir/glsl/type.go
@@ -61,7 +61,7 @@ func opString(op shaderir.Op) string {
 	case shaderir.OrOr:
 		return "||"
 	}
-	return fmt.Sprintf("!(unexpected operator: %d)", op)
+	return fmt.Sprintf("?(unexpected operator: %d)", op)
 }
 
 func typeString(t *shaderir.Type) (string, string) {
diff --git a/internal/shaderir/hlsl/type.go b/internal/shaderir/hlsl/type.go
index 10ae3792a..d69391d16 100644
--- a/internal/shaderir/hlsl/type.go
+++ b/internal/shaderir/hlsl/type.go
@@ -61,7 +61,7 @@ func opString(op shaderir.Op) string {
 	case shaderir.OrOr:
 		return "||"
 	}
-	return fmt.Sprintf("!(unexpected operator: %d)", op)
+	return fmt.Sprintf("?(unexpected operator: %d)", op)
 }
 
 func typeString(t *shaderir.Type) (string, string) {
diff --git a/internal/shaderir/msl/type.go b/internal/shaderir/msl/type.go
index 319b72b96..884be16c2 100644
--- a/internal/shaderir/msl/type.go
+++ b/internal/shaderir/msl/type.go
@@ -61,7 +61,7 @@ func opString(op shaderir.Op) string {
 	case shaderir.OrOr:
 		return "||"
 	}
-	return fmt.Sprintf("!(unexpected operator: %d)", op)
+	return fmt.Sprintf("?(unexpected operator: %d)", op)
 }
 
 func typeString(t *shaderir.Type, packed bool, ref bool) string {