diff --git a/testutil/rsyncserver/server.go b/testutil/rsyncserver/server.go
index 1732afc9..b15f713b 100644
--- a/testutil/rsyncserver/server.go
+++ b/testutil/rsyncserver/server.go
@@ -17,7 +17,7 @@ import (
 	"lvmsync_go/device"
 	"lvmsync_go/internal/digest"
 	"lvmsync_go/internal/rsyncwire"
-	"lvmsync_go/internal/signaturecache"
+	"lvmsync_go/testutil/signaturecache"
 )
 
 // Device represents a writable block device supporting random writes and sync.
diff --git a/testutil/rsyncserver/server_test.go b/testutil/rsyncserver/server_test.go
index eabf303d..c4d7aaa4 100644
--- a/testutil/rsyncserver/server_test.go
+++ b/testutil/rsyncserver/server_test.go
@@ -22,7 +22,7 @@ import (
 	"lvmsync_go/device"
 	"lvmsync_go/internal/digest"
 	"lvmsync_go/internal/rsyncwire"
-	"lvmsync_go/internal/signaturecache"
+	"lvmsync_go/testutil/signaturecache"
 )
 
 const maxFrame = 1 << 20
diff --git a/internal/signaturecache/cache.go b/testutil/signaturecache/cache.go
similarity index 99%
rename from internal/signaturecache/cache.go
rename to testutil/signaturecache/cache.go
index ed011d11..6e16debc 100644
--- a/internal/signaturecache/cache.go
+++ b/testutil/signaturecache/cache.go
@@ -1,3 +1,5 @@
+//go:build rsync
+
 package signaturecache
 
 import (
diff --git a/internal/signaturecache/cache_test.go b/testutil/signaturecache/cache_test.go
similarity index 99%
rename from internal/signaturecache/cache_test.go
rename to testutil/signaturecache/cache_test.go
index 48c262cc..61fb6297 100644
--- a/internal/signaturecache/cache_test.go
+++ b/testutil/signaturecache/cache_test.go
@@ -1,3 +1,5 @@
+//go:build rsync
+
 package signaturecache
 
 import (