diff --git a/Makefile b/Makefile
index f9505a2..d1eac44 100644
--- a/Makefile
+++ b/Makefile
@@ -24,5 +24,9 @@ build-arm64:
 	docker build -t sha1cd-arm64 -f Dockerfile.arm64 .
 	docker run --rm sha1cd-arm64
 
+# Build with cgo disabled.
+build-nocgo:
+	CGO_ENABLED=0 go build ./cgo
+
 # Run cross-compilation to assure supported architectures.
-cross-build: build-arm build-arm64
+cross-build: build-arm build-arm64 build-nocgo
diff --git a/cgo/fallback_no_cgo.go b/cgo/fallback_no_cgo.go
new file mode 100644
index 0000000..6e8bef2
--- /dev/null
+++ b/cgo/fallback_no_cgo.go
@@ -0,0 +1,32 @@
+//go:build !cgo
+// +build !cgo
+
+package cgo
+
+import (
+	"hash"
+
+	"github.com/pjbgf/sha1cd"
+	"github.com/pjbgf/sha1cd/ubc"
+)
+
+// CalculateDvMask falls back to github.com/pjbgf/sha1cd/ubc implementation
+// due to CGO being disabled at compilation time.
+func CalculateDvMask(W []uint32) (uint32, error) {
+	return ubc.CalculateDvMask(W)
+}
+
+// CalculateDvMask falls back to github.com/pjbgf/sha1cd implementation
+// due to CGO being disabled at compilation time.
+func New() hash.Hash {
+	return sha1cd.New()
+}
+
+// CalculateDvMask falls back to github.com/pjbgf/sha1cd implementation
+// due to CGO being disabled at compilation time.
+func Sum(data []byte) ([]byte, bool) {
+	d := sha1cd.New().(sha1cd.CollisionResistantHash)
+	d.Write(data)
+
+	return d.CollisionResistantSum(nil)
+}