diff --git a/src/front/glsl/functions.rs b/src/front/glsl/functions.rs
index fab1f5ae24..15d8ba7536 100644
--- a/src/front/glsl/functions.rs
+++ b/src/front/glsl/functions.rs
@@ -1,13 +1,35 @@
 use crate::{
-    proc::ensure_block_returns, Arena, BinaryOperator, Block, EntryPoint, Expression, Function,
+    proc::ensure_block_returns, Arena, BinaryOperator, Block, Constant, ConstantInner, EntryPoint, Expression, Function,
     FunctionArgument, FunctionResult, Handle, ImageQuery, LocalVariable, MathFunction,
-    RelationalFunction, SampleLevel, ScalarKind, Statement, StructMember, SwizzleComponent, Type,
+    RelationalFunction, SampleLevel, ScalarKind, ScalarValue, Statement, StructMember, SwizzleComponent, Type,
     TypeInner, VectorSize,
 };
 
 use super::{ast::*, error::ErrorKind, SourceMetadata};
 
 impl Program<'_> {
+    fn add_constant_value(
+        &mut self,
+        scalar_kind: ScalarKind,
+        value: u64,
+    ) -> Handle<Constant> {
+        let value = match scalar_kind {
+            ScalarKind::Uint => ScalarValue::Uint(value),
+            ScalarKind::Sint => ScalarValue::Sint(value as i64),
+            ScalarKind::Float => ScalarValue::Float(value as f64),
+            _ => unreachable!(),
+        };
+
+        self.module.constants.fetch_or_append(Constant {
+            name: None,
+            specialization: None,
+            inner: ConstantInner::Scalar {
+                width: 4,
+                value,
+            },
+        })
+    }
+
     pub fn function_call(
         &mut self,
         ctx: &mut Context,
@@ -24,13 +46,40 @@ impl Program<'_> {
         match fc {
             FunctionCallKind::TypeConstructor(ty) => {
                 let h = if args.len() == 1 {
-                    let is_vec = match *self.resolve_type(ctx, args[0].0, args[0].1)? {
-                        TypeInner::Vector { .. } => true,
-                        _ => false,
+                    let expr_type = self.resolve_type(ctx, args[0].0, args[0].1)?;
+
+                    let vector_size = match *expr_type {
+                        TypeInner::Vector{ size, .. } => Some(size),
+                        _ => None,
                     };
 
+                    // Special case: if casting from a bool, we need to use Select and not As.
+                    match self.module.types[ty].inner.scalar_kind() {
+                        Some(result_scalar_kind) if expr_type.scalar_kind() == Some(ScalarKind::Bool) && result_scalar_kind != ScalarKind::Bool => {
+                            let c0 = self.add_constant_value(result_scalar_kind, 0u64);
+                            let c1 = self.add_constant_value(result_scalar_kind, 1u64);
+                            let mut reject = ctx.add_expression(Expression::Constant(c0), body);
+                            let mut accept = ctx.add_expression(Expression::Constant(c1), body);
+
+                            ctx.implicit_splat(self, &mut reject, meta, vector_size)?;
+                            ctx.implicit_splat(self, &mut accept, meta, vector_size)?;
+
+                            let h = ctx.add_expression(
+                                Expression::Select {
+                                    accept,
+                                    reject,
+                                    condition: args[0].0,
+                                },
+                                body,
+                            );
+
+                            return Ok(Some(h));
+                        }
+                        _ => {}
+                    }
+
                     match self.module.types[ty].inner {
-                        TypeInner::Vector { size, kind, .. } if !is_vec => {
+                        TypeInner::Vector { size, kind, .. } if vector_size.is_none() => {
                             let (mut value, meta) = args[0];
                             ctx.implicit_conversion(self, &mut value, meta, kind)?;
 
diff --git a/src/valid/expression.rs b/src/valid/expression.rs
index d1bb45f7bf..990026d9b2 100644
--- a/src/valid/expression.rs
+++ b/src/valid/expression.rs
@@ -1159,13 +1159,15 @@ impl super::Validator {
                     .resolve(expr)?
                     .scalar_kind()
                     .ok_or(ExpressionError::InvalidCastArgument)?;
+
+                if prev_kind == Sk::Bool || kind == Sk::Bool {
+                    return Err(ExpressionError::InvalidCastArgument);
+                }
+
                 match convert {
                     Some(width) if !self.check_width(kind, width) => {
                         return Err(ExpressionError::InvalidCastArgument)
                     }
-                    None if prev_kind == Sk::Bool || kind == Sk::Bool => {
-                        return Err(ExpressionError::InvalidCastArgument)
-                    }
                     _ => {}
                 }
                 ShaderStages::all()
diff --git a/tests/in/glsl/bool-select.frag b/tests/in/glsl/bool-select.frag
new file mode 100644
index 0000000000..96cd7d4ae8
--- /dev/null
+++ b/tests/in/glsl/bool-select.frag
@@ -0,0 +1,17 @@
+#version 440 core
+precision highp float;
+
+layout(location = 0) out vec4 o_color;
+
+float TevPerCompGT(float a, float b) {
+    return float(a > b);
+}
+
+vec3 TevPerCompGT(vec3 a, vec3 b) {
+    return vec3(greaterThan(a, b));
+}
+
+void main() {
+    o_color.rgb = TevPerCompGT(vec3(3.0), vec3(5.0));
+    o_color.a = TevPerCompGT(3.0, 5.0);
+}
diff --git a/tests/out/wgsl/bool-select-frag.wgsl b/tests/out/wgsl/bool-select-frag.wgsl
new file mode 100644
index 0000000000..51524143bc
--- /dev/null
+++ b/tests/out/wgsl/bool-select-frag.wgsl
@@ -0,0 +1,45 @@
+struct FragmentOutput {
+    [[location(0), interpolate(perspective)]] o_color: vec4<f32>;
+};
+
+var<private> o_color: vec4<f32>;
+
+fn TevPerCompGT(a: f32, b: f32) -> f32 {
+    var a1: f32;
+    var b1: f32;
+
+    a1 = a;
+    b1 = b;
+    let _e5: f32 = a1;
+    let _e6: f32 = b1;
+    return select(1.0, 0.0, (_e5 > _e6));
+}
+
+fn TevPerCompGT1(a2: vec3<f32>, b2: vec3<f32>) -> vec3<f32> {
+    var a3: vec3<f32>;
+    var b3: vec3<f32>;
+
+    a3 = a2;
+    b3 = b2;
+    let _e5: vec3<f32> = a3;
+    let _e6: vec3<f32> = b3;
+    return select(vec3<f32>(1.0), vec3<f32>(0.0), (_e5 > _e6));
+}
+
+fn main1() {
+    let _e1: vec4<f32> = o_color;
+    let _e11: vec3<f32> = TevPerCompGT1(vec3<f32>(3.0), vec3<f32>(5.0));
+    o_color.x = _e11.x;
+    o_color.y = _e11.y;
+    o_color.z = _e11.z;
+    let _e23: f32 = TevPerCompGT(3.0, 5.0);
+    o_color.w = _e23;
+    return;
+}
+
+[[stage(fragment)]]
+fn main() -> FragmentOutput {
+    main1();
+    let _e1: vec4<f32> = o_color;
+    return FragmentOutput(_e1);
+}