diff --git a/util-tracking/src/main/scala/sbt/util/Tracked.scala b/util-tracking/src/main/scala/sbt/util/Tracked.scala
index 66e84e8fb..823e9bde9 100644
--- a/util-tracking/src/main/scala/sbt/util/Tracked.scala
+++ b/util-tracking/src/main/scala/sbt/util/Tracked.scala
@@ -96,16 +96,20 @@ object Tracked {
 
   private final class CacheHelp[I: JsonFormat](val sc: SingletonCache[Long]) {
     import CacheImplicits.implicitHashWriter
+    import CacheImplicits.LongJsonFormat
     def save(store: CacheStore, value: I): Unit = {
-      store.write(value)
+      Hasher.hash(value) match {
+        case Success(keyHash) => store.write[Long](keyHash.toLong)
+        case Failure(e)       => ()
+      }
     }
 
     def changed(store: CacheStore, value: I): Boolean =
-      Try { store.read[I] } match {
-        case Success(prev) =>
+      Try { store.read[Long] } match {
+        case Success(prev: Long) =>
           Hasher.hash(value) match {
-            case Success(keyHash) => keyHash.toLong != prev
-            case Failure(_)       => true
+            case Success(keyHash: Int) => keyHash.toLong != prev
+            case Failure(_)            => true
           }
         case Failure(_) => true
       }
diff --git a/util-tracking/src/test/scala/sbt/util/TrackedSpec.scala b/util-tracking/src/test/scala/sbt/util/TrackedSpec.scala
index 90513cad6..4fa480ca7 100644
--- a/util-tracking/src/test/scala/sbt/util/TrackedSpec.scala
+++ b/util-tracking/src/test/scala/sbt/util/TrackedSpec.scala
@@ -51,10 +51,10 @@ class TrackedSpec extends UnitSpec {
 
   "inputChanged" should "detect that the input has not changed" in {
     withStore { store =>
-      val input0 = 0
+      val input0 = "foo"
 
       val res0 =
-        Tracked.inputChanged[Int, Int](store) {
+        Tracked.inputChanged[String, String](store) {
           case (true, in) =>
             assert(in === input0)
             in
@@ -64,7 +64,7 @@ class TrackedSpec extends UnitSpec {
       assert(res0 === input0)
 
       val res1 =
-        Tracked.inputChanged[Int, Int](store) {
+        Tracked.inputChanged[String, String](store) {
           case (true, in) =>
             fail()
           case (false, in) =>