diff --git a/rten-vecmath/src/simd_vec.rs b/rten-vecmath/src/simd_vec.rs
index 864f185f..f2660021 100644
--- a/rten-vecmath/src/simd_vec.rs
+++ b/rten-vecmath/src/simd_vec.rs
@@ -34,6 +34,9 @@ pub trait SimdInt: Copy + Sized {
     /// vector to a float.
     type Float: SimdFloat<Int = Self>;
 
+    /// The type used by operations that use or return masks.
+    type Mask: Copy;
+
     /// Return a new vector with all elements set to zero.
     unsafe fn zero() -> Self {
         Self::splat(0)
@@ -43,13 +46,13 @@ pub trait SimdInt: Copy + Sized {
     unsafe fn splat(val: i32) -> Self;
 
     /// Return a mask indicating whether `self > other`.
-    unsafe fn gt(self, other: Self) -> Self;
+    unsafe fn gt(self, other: Self) -> Self::Mask;
 
     /// Select elements from this vector or `other` according to a mask.
     ///
     /// For each lane, if the mask value is zero, return the element from
     /// `self`, otherwise return the value from `other`.
-    unsafe fn blend(self, other: Self, mask: Self) -> Self;
+    unsafe fn blend(self, other: Self, mask: Self::Mask) -> Self;
 
     /// Compute `self + rhs`.
     unsafe fn add(self, rhs: Self) -> Self;
@@ -96,6 +99,9 @@ pub trait SimdFloat: Copy + Sized {
     /// to a vector of ints.
     type Int: SimdInt<Float = Self>;
 
+    /// The type used by operations that use or return masks.
+    type Mask: Copy;
+
     /// Shorthand for `Self::splat(1.0)`.
     unsafe fn one() -> Self {
         Self::splat(1.0)
@@ -141,13 +147,13 @@ pub trait SimdFloat: Copy + Sized {
     unsafe fn div(self, rhs: Self) -> Self;
 
     /// Compute a mask containing `self >= rhs`.
-    unsafe fn ge(self, rhs: Self) -> Self;
+    unsafe fn ge(self, rhs: Self) -> Self::Mask;
 
     /// Compute a mask containing `self <= rhs`.
-    unsafe fn le(self, rhs: Self) -> Self;
+    unsafe fn le(self, rhs: Self) -> Self::Mask;
 
     /// Compute a mask containing `self < rhs`.
-    unsafe fn lt(self, rhs: Self) -> Self;
+    unsafe fn lt(self, rhs: Self) -> Self::Mask;
 
     /// Compute the maximum of `self` and `rhs`.
     unsafe fn max(self, rhs: Self) -> Self;
@@ -156,7 +162,7 @@ pub trait SimdFloat: Copy + Sized {
     ///
     /// For each lane, if the mask value is zero, return the element from
     /// `self`, otherwise return the value from `other`.
-    unsafe fn blend(self, other: Self, mask: Self) -> Self;
+    unsafe fn blend(self, other: Self, mask: Self::Mask) -> Self;
 
     /// Evaluate a polynomial using Horner's method.
     ///
@@ -200,6 +206,7 @@ impl SimdInt for i32 {
     const LEN: usize = 1;
 
     type Float = f32;
+    type Mask = bool;
 
     unsafe fn zero() -> Self {
         0
@@ -209,12 +216,12 @@ impl SimdInt for i32 {
         val
     }
 
-    unsafe fn gt(self, other: Self) -> Self {
-        (self > other) as i32
+    unsafe fn gt(self, other: Self) -> Self::Mask {
+        self > other
     }
 
-    unsafe fn blend(self, other: Self, mask: Self) -> Self {
-        if mask == 0 {
+    unsafe fn blend(self, other: Self, mask: Self::Mask) -> Self {
+        if !mask {
             self
         } else {
             other
@@ -251,6 +258,7 @@ impl SimdFloat for f32 {
     const LEN: usize = 1;
 
     type Int = i32;
+    type Mask = bool;
 
     unsafe fn one() -> Self {
         1.
@@ -292,36 +300,24 @@ impl SimdFloat for f32 {
         self / rhs
     }
 
-    unsafe fn ge(self, rhs: Self) -> Self {
-        if self >= rhs {
-            1.
-        } else {
-            0.
-        }
+    unsafe fn ge(self, rhs: Self) -> Self::Mask {
+        self >= rhs
     }
 
-    unsafe fn le(self, rhs: Self) -> Self {
-        if self <= rhs {
-            1.
-        } else {
-            0.
-        }
+    unsafe fn le(self, rhs: Self) -> Self::Mask {
+        self <= rhs
     }
 
-    unsafe fn lt(self, rhs: Self) -> Self {
-        if self < rhs {
-            1.
-        } else {
-            0.
-        }
+    unsafe fn lt(self, rhs: Self) -> Self::Mask {
+        self < rhs
     }
 
     unsafe fn max(self, rhs: Self) -> Self {
         f32::max(self, rhs)
     }
 
-    unsafe fn blend(self, rhs: Self, mask: Self) -> Self {
-        if mask == 0. {
+    unsafe fn blend(self, rhs: Self, mask: Self::Mask) -> Self {
+        if !mask {
             self
         } else {
             rhs
diff --git a/rten-vecmath/src/simd_vec/aarch64.rs b/rten-vecmath/src/simd_vec/aarch64.rs
index e2e5b3c8..197dc36b 100644
--- a/rten-vecmath/src/simd_vec/aarch64.rs
+++ b/rten-vecmath/src/simd_vec/aarch64.rs
@@ -1,15 +1,15 @@
 use std::arch::aarch64::{
-    float32x4_t, int32x4_t, vabsq_f32, vaddq_f32, vaddq_s32, vbslq_f32, vbslq_s32, vcgeq_f32,
-    vcgtq_s32, vcleq_f32, vcltq_f32, vcvtq_s32_f32, vdivq_f32, vdupq_n_f32, vdupq_n_s32, vfmaq_f32,
-    vld1q_f32, vld1q_s32, vmaxq_f32, vmulq_f32, vreinterpretq_f32_s32, vreinterpretq_f32_u32,
-    vreinterpretq_s32_u32, vreinterpretq_u32_f32, vreinterpretq_u32_s32, vshlq_n_s32, vst1q_f32,
-    vst1q_s32, vsubq_f32, vsubq_s32,
+    float32x4_t, int32x4_t, uint32x4_t, vabsq_f32, vaddq_f32, vaddq_s32, vbslq_f32, vbslq_s32,
+    vcgeq_f32, vcgtq_s32, vcleq_f32, vcltq_f32, vcvtq_s32_f32, vdivq_f32, vdupq_n_f32, vdupq_n_s32,
+    vfmaq_f32, vld1q_f32, vld1q_s32, vmaxq_f32, vmulq_f32, vreinterpretq_f32_s32, vshlq_n_s32,
+    vst1q_f32, vst1q_s32, vsubq_f32, vsubq_s32,
 };
 
 use crate::simd_vec::{SimdFloat, SimdInt};
 
 impl SimdInt for int32x4_t {
     type Float = float32x4_t;
+    type Mask = uint32x4_t;
 
     const LEN: usize = 4;
 
@@ -21,12 +21,12 @@ impl SimdInt for int32x4_t {
         vdupq_n_s32(val)
     }
 
-    unsafe fn gt(self, other: Self) -> Self {
-        vreinterpretq_s32_u32(vcgtq_s32(self, other))
+    unsafe fn gt(self, other: Self) -> Self::Mask {
+        vcgtq_s32(self, other)
     }
 
-    unsafe fn blend(self, other: Self, mask: Self) -> Self {
-        vbslq_s32(vreinterpretq_u32_s32(mask), other, self)
+    unsafe fn blend(self, other: Self, mask: Self::Mask) -> Self {
+        vbslq_s32(mask, other, self)
     }
 
     unsafe fn add(self, rhs: Self) -> Self {
@@ -56,6 +56,7 @@ impl SimdInt for int32x4_t {
 
 impl SimdFloat for float32x4_t {
     type Int = int32x4_t;
+    type Mask = uint32x4_t;
 
     const LEN: usize = 4;
 
@@ -91,24 +92,24 @@ impl SimdFloat for float32x4_t {
         vdivq_f32(self, rhs)
     }
 
-    unsafe fn ge(self, rhs: Self) -> Self {
-        vreinterpretq_f32_u32(vcgeq_f32(self, rhs))
+    unsafe fn ge(self, rhs: Self) -> Self::Mask {
+        vcgeq_f32(self, rhs)
     }
 
-    unsafe fn le(self, rhs: Self) -> Self {
-        vreinterpretq_f32_u32(vcleq_f32(self, rhs))
+    unsafe fn le(self, rhs: Self) -> Self::Mask {
+        vcleq_f32(self, rhs)
     }
 
-    unsafe fn lt(self, rhs: Self) -> Self {
-        vreinterpretq_f32_u32(vcltq_f32(self, rhs))
+    unsafe fn lt(self, rhs: Self) -> Self::Mask {
+        vcltq_f32(self, rhs)
     }
 
     unsafe fn max(self, rhs: Self) -> Self {
         vmaxq_f32(self, rhs)
     }
 
-    unsafe fn blend(self, other: Self, mask: Self) -> Self {
-        vbslq_f32(vreinterpretq_u32_f32(mask), other, self)
+    unsafe fn blend(self, other: Self, mask: Self::Mask) -> Self {
+        vbslq_f32(mask, other, self)
     }
 
     unsafe fn load(ptr: *const f32) -> Self {
diff --git a/rten-vecmath/src/simd_vec/wasm.rs b/rten-vecmath/src/simd_vec/wasm.rs
index a8ec5f45..9d4b9e9f 100644
--- a/rten-vecmath/src/simd_vec/wasm.rs
+++ b/rten-vecmath/src/simd_vec/wasm.rs
@@ -18,6 +18,7 @@ pub struct v128f(v128);
 
 impl SimdInt for v128i {
     type Float = v128f;
+    type Mask = v128i;
 
     const LEN: usize = 4;
 
@@ -25,11 +26,11 @@ impl SimdInt for v128i {
         Self(i32x4_splat(val))
     }
 
-    unsafe fn gt(self, other: Self) -> Self {
+    unsafe fn gt(self, other: Self) -> Self::Mask {
         Self(i32x4_gt(self.0, other.0))
     }
 
-    unsafe fn blend(self, other: Self, mask: Self) -> Self {
+    unsafe fn blend(self, other: Self, mask: Self::Mask) -> Self {
         Self(v128_bitselect(other.0, self.0, mask.0))
     }
 
@@ -60,6 +61,7 @@ impl SimdInt for v128i {
 
 impl SimdFloat for v128f {
     type Int = v128i;
+    type Mask = v128i;
 
     const LEN: usize = 4;
 
@@ -95,23 +97,23 @@ impl SimdFloat for v128f {
         Self(f32x4_div(self.0, rhs.0))
     }
 
-    unsafe fn ge(self, rhs: Self) -> Self {
-        Self(f32x4_ge(self.0, rhs.0))
+    unsafe fn ge(self, rhs: Self) -> Self::Mask {
+        v128i(f32x4_ge(self.0, rhs.0))
     }
 
-    unsafe fn le(self, rhs: Self) -> Self {
-        Self(f32x4_le(self.0, rhs.0))
+    unsafe fn le(self, rhs: Self) -> Self::Mask {
+        v128i(f32x4_le(self.0, rhs.0))
     }
 
-    unsafe fn lt(self, rhs: Self) -> Self {
-        Self(f32x4_lt(self.0, rhs.0))
+    unsafe fn lt(self, rhs: Self) -> Self::Mask {
+        v128i(f32x4_lt(self.0, rhs.0))
     }
 
     unsafe fn max(self, rhs: Self) -> Self {
         Self(f32x4_max(self.0, rhs.0))
     }
 
-    unsafe fn blend(self, rhs: Self, mask: Self) -> Self {
+    unsafe fn blend(self, rhs: Self, mask: Self::Mask) -> Self {
         Self(v128_bitselect(rhs.0, self.0, mask.0))
     }
 
diff --git a/rten-vecmath/src/simd_vec/x86_64.rs b/rten-vecmath/src/simd_vec/x86_64.rs
index a6cf201b..073f198c 100644
--- a/rten-vecmath/src/simd_vec/x86_64.rs
+++ b/rten-vecmath/src/simd_vec/x86_64.rs
@@ -11,6 +11,7 @@ use crate::simd_vec::{SimdFloat, SimdInt};
 
 impl SimdInt for __m256i {
     type Float = __m256;
+    type Mask = __m256i;
 
     const LEN: usize = 8;
 
@@ -28,13 +29,13 @@ impl SimdInt for __m256i {
 
     #[target_feature(enable = "avx2")]
     #[target_feature(enable = "fma")]
-    unsafe fn gt(self, other: Self) -> Self {
+    unsafe fn gt(self, other: Self) -> Self::Mask {
         _mm256_cmpgt_epi32(self, other)
     }
 
     #[target_feature(enable = "avx2")]
     #[target_feature(enable = "fma")]
-    unsafe fn blend(self, other: Self, mask: Self) -> Self {
+    unsafe fn blend(self, other: Self, mask: Self::Mask) -> Self {
         _mm256_blendv_epi8(self, other, mask)
     }
 
@@ -79,6 +80,7 @@ impl SimdInt for __m256i {
 
 impl SimdFloat for __m256 {
     type Int = __m256i;
+    type Mask = __m256;
 
     const LEN: usize = 8;
 
@@ -134,19 +136,19 @@ impl SimdFloat for __m256 {
 
     #[target_feature(enable = "avx2")]
     #[target_feature(enable = "fma")]
-    unsafe fn ge(self, rhs: Self) -> Self {
+    unsafe fn ge(self, rhs: Self::Mask) -> Self {
         _mm256_cmp_ps(self, rhs, _CMP_GE_OQ)
     }
 
     #[target_feature(enable = "avx2")]
     #[target_feature(enable = "fma")]
-    unsafe fn le(self, rhs: Self) -> Self {
+    unsafe fn le(self, rhs: Self::Mask) -> Self {
         _mm256_cmp_ps(self, rhs, _CMP_LE_OQ)
     }
 
     #[target_feature(enable = "avx2")]
     #[target_feature(enable = "fma")]
-    unsafe fn lt(self, rhs: Self) -> Self {
+    unsafe fn lt(self, rhs: Self::Mask) -> Self {
         _mm256_cmp_ps(self, rhs, _CMP_LT_OQ)
     }
 
@@ -158,7 +160,7 @@ impl SimdFloat for __m256 {
 
     #[target_feature(enable = "avx2")]
     #[target_feature(enable = "fma")]
-    unsafe fn blend(self, rhs: Self, mask: Self) -> Self {
+    unsafe fn blend(self, rhs: Self, mask: Self::Mask) -> Self {
         _mm256_blendv_ps(self, rhs, mask)
     }