diff --git a/candle-core/src/cuda_backend.rs b/candle-core/src/cuda_backend.rs
index 7d06dd72..0e9c11c8 100644
--- a/candle-core/src/cuda_backend.rs
+++ b/candle-core/src/cuda_backend.rs
@@ -244,6 +244,7 @@ enum CudaStorageSlice {
     F32(CudaSlice<f32>),
     F64(CudaSlice<f64>),
 }
+type S = CudaStorageSlice;
 
 trait Map1 {
     fn f<T: DeviceRepr + WithDType + ValidAsZeroBits>(
@@ -253,13 +254,36 @@ trait Map1 {
         layout: &Layout,
     ) -> Result<CudaSlice<T>>;
 
-    fn map(&self, s: &CudaStorageSlice, d: &CudaDevice, l: &Layout) -> Result<CudaStorageSlice> {
+    fn map(&self, s: &S, d: &CudaDevice, l: &Layout) -> Result<S> {
         let out = match s {
-            CudaStorageSlice::U32(s) => CudaStorageSlice::U32(self.f(s, d, l)?),
-            CudaStorageSlice::BF16(s) => CudaStorageSlice::BF16(self.f(s, d, l)?),
-            CudaStorageSlice::F16(s) => CudaStorageSlice::F16(self.f(s, d, l)?),
-            CudaStorageSlice::F32(s) => CudaStorageSlice::F32(self.f(s, d, l)?),
-            CudaStorageSlice::F64(s) => CudaStorageSlice::F64(self.f(s, d, l)?),
+            S::U32(s) => S::U32(self.f(s, d, l)?),
+            S::BF16(s) => S::BF16(self.f(s, d, l)?),
+            S::F16(s) => S::F16(self.f(s, d, l)?),
+            S::F32(s) => S::F32(self.f(s, d, l)?),
+            S::F64(s) => S::F64(self.f(s, d, l)?),
+        };
+        Ok(out)
+    }
+}
+
+trait Map2 {
+    fn f<T: DeviceRepr + WithDType + ValidAsZeroBits>(
+        &self,
+        src1: &CudaSlice<T>,
+        layout1: &Layout,
+        src2: &CudaSlice<T>,
+        layout2: &Layout,
+        dev: &CudaDevice,
+    ) -> Result<CudaSlice<T>>;
+
+    fn map(&self, s1: &S, l1: &Layout, s2: &S, l2: &Layout, d: &CudaDevice) -> Result<S> {
+        let out = match (s1, s2) {
+            (S::U32(s1), S::U32(s2)) => S::U32(self.f(s1, l1, s2, l2, d)?),
+            (S::BF16(s1), S::BF16(s2)) => S::BF16(self.f(s1, l1, s2, l2, d)?),
+            (S::F16(s1), S::F16(s2)) => S::F16(self.f(s1, l1, s2, l2, d)?),
+            (S::F32(s1), S::F32(s2)) => S::F32(self.f(s1, l1, s2, l2, d)?),
+            (S::F64(s1), S::F64(s2)) => S::F64(self.f(s1, l1, s2, l2, d)?),
+            _ => return Err(CudaError::InternalError("dtype mismatch in binary op")),
         };
         Ok(out)
     }
@@ -411,6 +435,44 @@ impl<'a> Map1 for Embedding<'a> {
     }
 }
 
+struct WhereCond<'a>(&'a CudaStorage, &'a Layout);
+impl<'a> Map2 for WhereCond<'a> {
+    fn f<T: DeviceRepr + WithDType + ValidAsZeroBits>(
+        &self,
+        t: &CudaSlice<T>,
+        layout_t: &Layout,
+        f: &CudaSlice<T>,
+        layout_f: &Layout,
+        dev: &CudaDevice,
+    ) -> Result<CudaSlice<T>> {
+        let ids_l = &self.1;
+        let ids = match &self.0.slice {
+            CudaStorageSlice::U32(slice) => slice.slice(ids_l.start_offset()..),
+            _ => Err(CudaError::UnexpectedDType {
+                msg: "where conditions should be u32",
+                expected: DType::U32,
+                got: self.0.dtype(),
+            })?,
+        };
+        let ids = &ids;
+        let shape = ids_l.shape();
+        let dims = shape.dims();
+        let el = shape.elem_count();
+        let cfg = LaunchConfig::for_num_elems(el as u32);
+        let ds =
+            dev.htod_copy([dims, ids_l.stride(), layout_t.stride(), layout_f.stride()].concat())?;
+        let t = &t.slice(layout_t.start_offset()..);
+        let f = &f.slice(layout_f.start_offset()..);
+        let func = dev.get_or_load_func(&kernel_name::<T>("where"), kernels::TERNARY)?;
+        // SAFETY: Set later by running the kernel.
+        let out = unsafe { dev.alloc::<T>(el) }?;
+        let params = (el, dims.len(), &ds, ids, t, f, &out);
+        // SAFETY: ffi
+        unsafe { func.launch(cfg, params) }?;
+        Ok(out)
+    }
+}
+
 fn slice_src_and_dst<'a, T>(
     src: &'a CudaSlice<T>,
     src_l: &Layout,
@@ -714,86 +776,12 @@ impl CudaStorage {
         &self,
         layout: &Layout,
         t: &Self,
-        layout_t: &Layout,
+        t_l: &Layout,
         f: &Self,
-        layout_f: &Layout,
+        f_l: &Layout,
     ) -> Result<Self> {
-        let ids = match &self.slice {
-            CudaStorageSlice::U32(slice) => slice.slice(layout.start_offset()..),
-            _ => Err(CudaError::UnexpectedDType {
-                msg: "where conditions should be u32",
-                expected: DType::U32,
-                got: self.dtype(),
-            })?,
-        };
-        let ids = &ids;
-        let shape = layout.shape();
-        let dims = shape.dims();
-        let el = shape.elem_count();
-        let cfg = LaunchConfig::for_num_elems(el as u32);
-        let dev = self.device();
-        let ds =
-            dev.htod_copy([dims, layout.stride(), layout_t.stride(), layout_f.stride()].concat())?;
-        let slice = match (&t.slice, &f.slice) {
-            (CudaStorageSlice::BF16(t), CudaStorageSlice::BF16(f)) => {
-                let t = &t.slice(layout_t.start_offset()..);
-                let f = &f.slice(layout_f.start_offset()..);
-                let func = dev.get_or_load_func("where_bf16", kernels::TERNARY)?;
-                // SAFETY: Set later by running the kernel.
-                let out = unsafe { dev.alloc::<bf16>(el) }?;
-                let params = (el, dims.len(), &ds, ids, t, f, &out);
-                // SAFETY: ffi
-                unsafe { func.launch(cfg, params) }?;
-                CudaStorageSlice::BF16(out)
-            }
-            (CudaStorageSlice::F16(t), CudaStorageSlice::F16(f)) => {
-                let t = &t.slice(layout_t.start_offset()..);
-                let f = &f.slice(layout_f.start_offset()..);
-                let func = dev.get_or_load_func("where_f16", kernels::TERNARY)?;
-                // SAFETY: Set later by running the kernel.
-                let out = unsafe { dev.alloc::<f16>(el) }?;
-                let params = (el, dims.len(), &ds, ids, t, f, &out);
-                // SAFETY: ffi
-                unsafe { func.launch(cfg, params) }?;
-                CudaStorageSlice::F16(out)
-            }
-            (CudaStorageSlice::F32(t), CudaStorageSlice::F32(f)) => {
-                let t = &t.slice(layout_t.start_offset()..);
-                let f = &f.slice(layout_f.start_offset()..);
-                let func = dev.get_or_load_func("where_f32", kernels::TERNARY)?;
-                // SAFETY: Set later by running the kernel.
-                let out = unsafe { dev.alloc::<f32>(el) }?;
-                let params = (el, dims.len(), &ds, ids, t, f, &out);
-                // SAFETY: ffi
-                unsafe { func.launch(cfg, params) }?;
-                CudaStorageSlice::F32(out)
-            }
-            (CudaStorageSlice::F64(t), CudaStorageSlice::F64(f)) => {
-                let t = &t.slice(layout_t.start_offset()..);
-                let f = &f.slice(layout_f.start_offset()..);
-                // SAFETY: Set later by running the kernel.
-                let func = dev.get_or_load_func("where_f64", kernels::TERNARY)?;
-                let out = unsafe { dev.alloc::<f64>(el) }?;
-                let params = (el, dims.len(), &ds, ids, t, f, &out);
-                // SAFETY: ffi
-                unsafe { func.launch(cfg, params) }?;
-                CudaStorageSlice::F64(out)
-            }
-            (CudaStorageSlice::U32(t), CudaStorageSlice::U32(f)) => {
-                let t = &t.slice(layout_t.start_offset()..);
-                let f = &f.slice(layout_f.start_offset()..);
-                // SAFETY: Set later by running the kernel.
-                let func = dev.get_or_load_func("where_u32", kernels::TERNARY)?;
-                let out = unsafe { dev.alloc::<u32>(el) }?;
-                let params = (el, dims.len(), &ds, ids, t, f, &out);
-                // SAFETY: ffi
-                unsafe { func.launch(cfg, params) }?;
-                CudaStorageSlice::U32(out)
-            }
-            // The dtypes should have been checked at this point so this is an internal error.
-            _ => Err(CudaError::InternalError("dtype mismatch in binary op"))?,
-        };
-        let device = dev.clone();
+        let device = self.device().clone();
+        let slice = WhereCond(self, layout).map(&t.slice, t_l, &f.slice, f_l, &device)?;
         Ok(Self { slice, device })
     }