diff --git a/gearslip/src/main/java/app/seb3thehacker/gearslip/host/CarAppConnection.kt b/gearslip/src/main/java/app/seb3thehacker/gearslip/host/CarAppConnection.kt
index dbca04d..d506129 100644
--- a/gearslip/src/main/java/app/seb3thehacker/gearslip/host/CarAppConnection.kt
+++ b/gearslip/src/main/java/app/seb3thehacker/gearslip/host/CarAppConnection.kt
@@ -226,6 +226,7 @@ class CarAppConnection(private val context: Context) {
     fun disconnect() = disconnect(keepLocation = false)
 
     private fun disconnect(keepLocation: Boolean) {
+        main.removeCallbacks(handshakeTimeout)
         clearToasts()
         lent?.let { sendSurfaceDestroyed(it) }
         lent = null
@@ -257,11 +258,24 @@ class CarAppConnection(private val context: Context) {
 
     // --- handshake ---------------------------------------------------------------------
 
+    /**
+     * An app that won't have Gearslip as its host never answers the first question. Car App
+     * Library 1.9 and later throw inside the app when a host that isn't Google's asks, and since
+     * the call is one-way the error never comes back, so without this the car would show
+     * "Starting..." for ever.
+     */
+    private val handshakeTimeout = Runnable {
+        if (_status.value.phase == Phase.HANDSHAKE) {
+            fail(Phase.REJECTED, "It didn't answer Gearslip. Apps built for newer versions of Android Auto only run on Google's.")
+        }
+    }
+
     private fun onBound(service: IBinder) {
         val app = ICarApp.Stub.asInterface(service)
         carApp = app
         update { it.copy(phase = Phase.HANDSHAKE, detail = "bound, asking for app info") }
         GearslipLog.i("host: bound; requesting app info")
+        main.postDelayed(handshakeTimeout, HANDSHAKE_TIMEOUT_MS)
 
         call("getAppInfo", onValue = { value ->
             val info = value as? AppInfo ?: return@call fail(Phase.FAILED, "app info was ${value?.javaClass?.simpleName}")
@@ -274,6 +288,7 @@ class CarAppConnection(private val context: Context) {
      * offers cannot be rendered correctly, so it is refused here rather than half-drawn.
      */
     private fun onAppInfo(info: AppInfo) {
+        main.removeCallbacks(handshakeTimeout)
         val negotiated = minOf(HOST_API_LEVEL, info.latestCarAppApiLevel)
         GearslipLog.i(
             "host: app api ${info.minCarAppApiLevel}..${info.latestCarAppApiLevel} " +
@@ -839,6 +854,9 @@ class CarAppConnection(private val context: Context) {
         /** How long a new destination waits for the old route to end; see [navigateTo]. */
         const val REROUTE_WAIT_MS = 1_500L
 
+        /** How long an app gets to answer the first question before it counts as refusing. */
+        const val HANDSHAKE_TIMEOUT_MS = 10_000L
+
         /** Context.BIND_FOREGROUND_SERVICE; the constant itself is hidden from the SDK. */
         const val BIND_FOREGROUND_SERVICE = 0x04000000
     }