diff --git a/.github/workflows/go.yml b/.github/workflows/go.yml
index c3b244b..82eef3e 100644
--- a/.github/workflows/go.yml
+++ b/.github/workflows/go.yml
@@ -7,12 +7,13 @@ on:
     branches: [ '*' ]
 
 jobs:
-  build:
-    runs-on: ubuntu-latest
+  supported:
     strategy:
       matrix:
         go: [ '1.21', '1.22' ]
-    name: Go ${{ matrix.go }} test
+        runner: [ 'ubuntu-latest', 'ubuntu-24.04-arm' ]
+    runs-on: ${{ matrix.runner }}
+    name: Go ${{ matrix.go }} ${{ matrix.runner }} supported test
     steps:
       - name: Set up Go 1.x
         uses: actions/setup-go@v4
@@ -23,11 +24,42 @@ jobs:
         uses: actions/checkout@v3
 
       - name: Get dependencies
-        run: |
-          go get -v -t -d ./...
+        run: go get -v -t -d ./...
 
       - name: Build
         run: go build -v ./...
 
       - name: Test
         run: go test -v ./...
+
+  unsupported:
+    strategy:
+      matrix:
+        go: [ '1.21', '1.22' ]
+    runs-on: ubuntu-latest
+    name: Go ${{ matrix.go }} unsupported test
+    steps:
+      - name: Update package index
+        run: sudo apt-get update
+
+      - name: install qemu
+        run: sudo apt install --yes qemu-user-static
+
+      - name: Set up Go 1.x
+        uses: actions/setup-go@v4
+        with:
+          go-version: ${{ matrix.go }}
+
+      - name: Check out code into the Go module directory
+        uses: actions/checkout@v3
+
+      - name: Get dependencies
+        run: go get -v -t -d ./...
+
+      - name: Build
+        run: GOARCH=riscv64 go build -v ./...
+
+      - name: Test
+        run: |
+          GOARCH=riscv64 go test -v ./... -c -o test.riscv64
+          qemu-riscv64-static test.riscv64 -test.v
diff --git a/LICENSE b/LICENSE
index 8d967ce..b6060be 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2022 Prysmatic Labs
+Copyright (c) 2022-2025 Prysmatic Labs
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/hash.go b/hash.go
index e009335..9c432e6 100644
--- a/hash.go
+++ b/hash.go
@@ -1,7 +1,7 @@
 /*
 MIT License
 
-# Copyright (c) 2021 Prysmatic Labs
+# Copyright (c) 2021-2025 Prysmatic Labs
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -28,8 +28,6 @@ import (
 	"unsafe"
 )
 
-func _hash(digests *byte, p [][32]byte, count uint32)
-
 // Hash hashes the chunks two at the time and outputs the digests on the first
 // argument. It does check for lengths on the inputs.
 func Hash(digests [][32]byte, chunks [][32]byte) error {
diff --git a/hash_amd64.go b/hash_amd64.go
index 7b53fcd..d39f04b 100644
--- a/hash_amd64.go
+++ b/hash_amd64.go
@@ -4,7 +4,7 @@
 /*
 MIT License
 
-Copyright (c) 2021 Prysmatic Labs
+Copyright (c) 2021-2025 Prysmatic Labs
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -34,3 +34,5 @@ var hasAVX512 = cpuid.CPU.Supports(cpuid.AVX512F, cpuid.AVX512VL)
 var hasAVX2 = cpuid.CPU.Supports(cpuid.AVX2, cpuid.BMI2)
 var hasShani = cpuid.CPU.Supports(cpuid.SHA, cpuid.AVX)
 var supportedCPU = hasAVX2 || hasShani || hasAVX512
+
+func _hash(digests *byte, p [][32]byte, count uint32)
diff --git a/hash_arm64.go b/hash_arm64.go
index ef86819..b54d0a5 100644
--- a/hash_arm64.go
+++ b/hash_arm64.go
@@ -4,7 +4,7 @@
 /*
 MIT License
 
-Copyright (c) 2021 Prysmatic Labs
+Copyright (c) 2021-2025 Prysmatic Labs
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
@@ -32,3 +32,5 @@ import (
 
 var hasShani = cpuid.CPU.Supports(cpuid.SHA2)
 var supportedCPU = true
+
+func _hash(digests *byte, p [][32]byte, count uint32)
diff --git a/hash_unsupported.go b/hash_unsupported.go
new file mode 100644
index 0000000..8db57c2
--- /dev/null
+++ b/hash_unsupported.go
@@ -0,0 +1,30 @@
+//go:build !amd64 && !arm64
+
+/*
+MIT License
+
+Copyright (c) 2025 Prysmatic Labs
+
+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.
+*/
+package gohashtree
+
+var supportedCPU = false
+
+func _hash(digests *byte, p [][32]byte, count uint32) {}