diff --git a/features/linknewdevice/impl/src/main/res/values/localazy.xml b/features/linknewdevice/impl/src/main/res/values/localazy.xml
index 9bf7ac2132..321b168751 100644
--- a/features/linknewdevice/impl/src/main/res/values/localazy.xml
+++ b/features/linknewdevice/impl/src/main/res/values/localazy.xml
@@ -38,6 +38,8 @@
   <string name="screen_qr_code_login_error_cancelled_title">"Sign in request cancelled"</string>
   <string name="screen_qr_code_login_error_declined_subtitle">"The sign in was declined on the other device."</string>
   <string name="screen_qr_code_login_error_declined_title">"Sign in declined"</string>
+  <string name="screen_qr_code_login_error_device_already_signed_in_subtitle">"You don’t need to do anything else."</string>
+  <string name="screen_qr_code_login_error_device_already_signed_in_title">"Your other device is already signed in"</string>
   <string name="screen_qr_code_login_error_expired_subtitle">"Sign in expired. Please try again."</string>
   <string name="screen_qr_code_login_error_expired_title">"The sign in was not completed in time"</string>
   <string name="screen_qr_code_login_error_linking_not_suported_subtitle">"Your other device does not support signing in to %s with a QR code.
diff --git a/features/login/impl/src/main/res/values/localazy.xml b/features/login/impl/src/main/res/values/localazy.xml
index 9b235558c8..832c3b7f71 100644
--- a/features/login/impl/src/main/res/values/localazy.xml
+++ b/features/login/impl/src/main/res/values/localazy.xml
@@ -60,6 +60,8 @@
   <string name="screen_qr_code_login_error_cancelled_title">"Sign in request cancelled"</string>
   <string name="screen_qr_code_login_error_declined_subtitle">"The sign in was declined on the other device."</string>
   <string name="screen_qr_code_login_error_declined_title">"Sign in declined"</string>
+  <string name="screen_qr_code_login_error_device_already_signed_in_subtitle">"You don’t need to do anything else."</string>
+  <string name="screen_qr_code_login_error_device_already_signed_in_title">"Your other device is already signed in"</string>
   <string name="screen_qr_code_login_error_expired_subtitle">"Sign in expired. Please try again."</string>
   <string name="screen_qr_code_login_error_expired_title">"The sign in was not completed in time"</string>
   <string name="screen_qr_code_login_error_linking_not_suported_subtitle">"Your other device does not support signing in to %s with a QR code.
diff --git a/libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/fixtures/fakes/FakeFfiCheckCodeSender.kt b/libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/fixtures/fakes/FakeFfiCheckCodeSender.kt
index 4bc6c212d2..a19c4e3766 100644
--- a/libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/fixtures/fakes/FakeFfiCheckCodeSender.kt
+++ b/libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/fixtures/fakes/FakeFfiCheckCodeSender.kt
@@ -7,7 +7,14 @@
 
 package io.element.android.libraries.matrix.impl.fixtures.fakes
 
+import io.element.android.tests.testutils.lambda.lambdaError
 import org.matrix.rustcomponents.sdk.CheckCodeSender
 import org.matrix.rustcomponents.sdk.NoHandle
 
-class FakeFfiCheckCodeSender : CheckCodeSender(NoHandle)
+class FakeFfiCheckCodeSender(
+    private val sendResult: (UByte) -> Unit = { _ -> lambdaError() }
+) : CheckCodeSender(NoHandle) {
+    override suspend fun send(code: UByte) {
+        sendResult(code)
+    }
+}
diff --git a/libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/linknewdevice/RustCheckCodeSenderTest.kt b/libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/linknewdevice/RustCheckCodeSenderTest.kt
new file mode 100644
index 0000000000..5fb4698976
--- /dev/null
+++ b/libraries/matrix/impl/src/test/kotlin/io/element/android/libraries/matrix/impl/linknewdevice/RustCheckCodeSenderTest.kt
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 2025 Element Creations Ltd.
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+ * Please see LICENSE files in the repository root for full details.
+ */
+
+package io.element.android.libraries.matrix.impl.linknewdevice
+
+import com.google.common.truth.Truth.assertThat
+import io.element.android.libraries.matrix.impl.fixtures.fakes.FakeFfiCheckCodeSender
+import io.element.android.tests.testutils.lambda.lambdaRecorder
+import io.element.android.tests.testutils.lambda.value
+import kotlinx.coroutines.test.StandardTestDispatcher
+import kotlinx.coroutines.test.runTest
+import org.junit.Test
+
+class RustCheckCodeSenderTest {
+    @Test
+    fun `send invokes the Ffi object`() = runTest {
+        val sendResult = lambdaRecorder<UByte, Unit> { }
+        val sut = RustCheckCodeSender(
+            inner = FakeFfiCheckCodeSender(
+                sendResult = sendResult,
+            ),
+            sessionDispatcher = StandardTestDispatcher(testScheduler),
+        )
+        sut.send(1.toUByte())
+        sendResult.assertions().isCalledOnce().with(value(1.toUByte()))
+    }
+
+    @Test
+    fun `validate always returns true for now`() = runTest {
+        val sut = RustCheckCodeSender(
+            inner = FakeFfiCheckCodeSender(),
+            sessionDispatcher = StandardTestDispatcher(testScheduler),
+        )
+        val result = sut.validate(1.toUByte())
+        assertThat(result).isTrue()
+    }
+}