diff --git a/Project.toml b/Project.toml
index 3f1e533419..08a8c4b331 100644
--- a/Project.toml
+++ b/Project.toml
@@ -37,11 +37,13 @@ Statistics = "10745b16-79ce-11e8-11f9-7d13ad32a3b2"
 demumble_jll = "1e29f10c-031c-5a83-9565-69cddfc27673"
 
 [weakdeps]
+Atomix = "a9b6321e-bd34-4604-b9c9-b65b8de01458"
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
 EnzymeCore = "f151be2c-9106-41f4-ab19-57ee4f262869"
 SpecialFunctions = "276daf66-3868-5448-9aa4-cd146d93841b"
 
 [extensions]
+AtomixExt = "Atomix"
 ChainRulesCoreExt = "ChainRulesCore"
 EnzymeCoreExt = "EnzymeCore"
 SpecialFunctionsExt = "SpecialFunctions"
@@ -49,6 +51,7 @@ SpecialFunctionsExt = "SpecialFunctions"
 [compat]
 AbstractFFTs = "0.4, 0.5, 1.0"
 Adapt = "4"
+Atomix = "0.1, 1"
 BFloat16s = "0.2, 0.3, 0.4, 0.5"
 CEnum = "0.2, 0.3, 0.4, 0.5"
 CUDA_Driver_jll = "0.10"
diff --git a/ext/AtomixExt.jl b/ext/AtomixExt.jl
new file mode 100644
index 0000000000..57495c7641
--- /dev/null
+++ b/ext/AtomixExt.jl
@@ -0,0 +1,83 @@
+#=
+MIT License
+
+Copyright (c) 2022 Takafumi Arakaki <aka.tkf@gmail.com> and contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+=#
+
+module AtomixExt
+
+# TODO: respect ordering
+
+using Atomix: Atomix, IndexableRef
+using CUDA: CUDA, CuDeviceArray
+
+const CuIndexableRef{Indexable<:CuDeviceArray} = IndexableRef{Indexable}
+
+function Atomix.get(ref::CuIndexableRef, order)
+    error("not implemented")
+end
+
+function Atomix.set!(ref::CuIndexableRef, v, order)
+    error("not implemented")
+end
+
+@inline function Atomix.replace!(
+    ref::CuIndexableRef,
+    expected,
+    desired,
+    success_ordering,
+    failure_ordering,
+)
+    ptr = Atomix.pointer(ref)
+    expected = convert(eltype(ref), expected)
+    desired = convert(eltype(ref), desired)
+    begin
+        old = CUDA.atomic_cas!(ptr, expected, desired)
+    end
+    return (; old = old, success = old === expected)
+end
+
+@inline function Atomix.modify!(ref::CuIndexableRef, op::OP, x, order) where {OP}
+    x = convert(eltype(ref), x)
+    ptr = Atomix.pointer(ref)
+    begin
+        old = if op === (+)
+            CUDA.atomic_add!(ptr, x)
+        elseif op === (-)
+            CUDA.atomic_sub!(ptr, x)
+        elseif op === (&)
+            CUDA.atomic_and!(ptr, x)
+        elseif op === (|)
+            CUDA.atomic_or!(ptr, x)
+        elseif op === xor
+            CUDA.atomic_xor!(ptr, x)
+        elseif op === min
+            CUDA.atomic_min!(ptr, x)
+        elseif op === max
+            CUDA.atomic_max!(ptr, x)
+        else
+            error("not implemented")
+        end
+    end
+    return old => op(old, x)
+end
+
+end  # module AtomixCUDA
diff --git a/test/Project.toml b/test/Project.toml
index 5d6ea83e88..728d7a8ed1 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -1,6 +1,7 @@
 [deps]
 AbstractFFTs = "621f4979-c628-5d54-868e-fcf4e3e8185c"
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"
+Atomix = "a9b6321e-bd34-4604-b9c9-b65b8de01458"
 BFloat16s = "ab4f0b2a-ad5b-11e8-123f-65d77653426b"
 CUDA_Driver_jll = "4ee394cb-3365-5eb0-8335-949819d2adfc"
 CUDA_Runtime_jll = "76a88914-d11a-5bdc-97e0-2f5a05c973a2"
diff --git a/test/base/atomix.jl b/test/base/atomix.jl
new file mode 100644
index 0000000000..47785d2190
--- /dev/null
+++ b/test/base/atomix.jl
@@ -0,0 +1,83 @@
+#=
+MIT License
+
+Copyright (c) 2022 Takafumi Arakaki <aka.tkf@gmail.com> and contributors
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+=#
+
+using Atomix
+using Test
+using CUDA
+
+function cuda(f)
+    function g()
+        f()
+        nothing
+    end
+    CUDA.@cuda g()
+end
+
+@testset "cas" begin
+    idx = (
+        data = 1,
+        cas1_ok = 2,
+        cas2_ok = 3,
+        # ...
+    )
+    @assert minimum(idx) >= 1
+    @assert maximum(idx) == length(idx)
+
+    A = CUDA.zeros(Int, length(idx))
+    cuda() do
+        GC.@preserve A begin
+            ref = Atomix.IndexableRef(A, (1,))
+            (old, success) = Atomix.replace!(ref, 0, 42)
+            A[idx.cas1_ok] = old == 0 && success
+            (old, success) = Atomix.replace!(ref, 0, 43)
+            A[idx.cas2_ok] = old == 42 && !success
+        end
+    end
+    @test collect(A) == [42, 1, 1]
+end
+
+@testset "inc" begin
+    @testset "core" begin
+        A = CUDA.CuVector(1:3)
+        cuda() do
+            GC.@preserve A begin
+                ref = Atomix.IndexableRef(A, (1,))
+                pre, post = Atomix.modify!(ref, +, 1)
+                A[2] = pre
+                A[3] = post
+            end
+        end
+        @test collect(A) == [2, 1, 2]
+    end
+
+    @testset "sugar" begin
+        A = CUDA.ones(Int, 3)
+        cuda() do
+            GC.@preserve A begin
+                Atomix.@atomic A[begin] += 1
+            end
+        end
+        @test collect(A) == [2, 1, 1]
+    end
+end