diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 88cc4ae..a9eb4f1 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -12,6 +12,7 @@ compose-bom = "2025.12.01"
 dokka = "2.1.0"
 junit = "4.13.2"
 kotlin = "2.2.21"
+kotlin-coroutines = "1.10.2"
 mockk = "1.14.7"
 okhttp = "5.3.2"
 
@@ -34,6 +35,7 @@ compose-ui-tooling = { module = "androidx.compose.ui:ui-tooling" }
 compose-ui-toolingPreview = { module = "androidx.compose.ui:ui-tooling-preview" }
 conscrypt = { module = "org.conscrypt:conscrypt-android", version.ref = "conscrypt" }
 junit = { module = "junit:junit", version.ref = "junit" }
+kotlin-coroutines-test = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-test", version.ref = "kotlin-coroutines" }
 kotlin-stdlib = { module = "org.jetbrains.kotlin:kotlin-stdlib", version.ref = "kotlin" }
 mockk-android = { module = "io.mockk:mockk-android", version.ref = "mockk" }
 okhttp = { module = "com.squareup.okhttp3:okhttp", version.ref = "okhttp" }
diff --git a/lib/build.gradle.kts b/lib/build.gradle.kts
index 294fd53..e9747ec 100644
--- a/lib/build.gradle.kts
+++ b/lib/build.gradle.kts
@@ -1,3 +1,13 @@
+/*
+ * Copyright © All Contributors. See LICENSE and AUTHORS in the root directory for details.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ */
+
 plugins {
     alias(libs.plugins.android.library)
     alias(libs.plugins.compose.compiler)
@@ -113,6 +123,7 @@ dependencies {
     androidTestImplementation(libs.androidx.test.runner)
     androidTestImplementation(libs.androidx.test.rules)
     androidTestImplementation(libs.conscrypt)
+    androidTestImplementation(libs.kotlin.coroutines.test)
     androidTestImplementation(libs.okhttp3.mockwebserver)
     androidTestImplementation(libs.mockk.android)
 
diff --git a/lib/src/androidTest/java/at/bitfire/cert4android/UserDecisionRegistryTest.kt b/lib/src/androidTest/java/at/bitfire/cert4android/UserDecisionRegistryTest.kt
index fd9d045..fe53491 100644
--- a/lib/src/androidTest/java/at/bitfire/cert4android/UserDecisionRegistryTest.kt
+++ b/lib/src/androidTest/java/at/bitfire/cert4android/UserDecisionRegistryTest.kt
@@ -23,6 +23,7 @@ import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.runBlocking
+import kotlinx.coroutines.test.runTest
 import org.junit.After
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertFalse
@@ -57,27 +58,24 @@ class UserDecisionRegistryTest {
 
 
     @Test
-    fun testCheck_FirstDecision_Negative() {
+    fun testCheck_FirstDecision_Negative() = runTest {
         every { registry.requestDecision(testCert, any(), any()) } answers {
             registry.onUserDecision(testCert, false)
         }
-        assertFalse(runBlocking {
-            registry.check(testCert, true)
-        })
+        assertFalse(registry.check(testCert, true))
     }
 
     @Test
-    fun testCheck_FirstDecision_Positive() {
+    fun testCheck_FirstDecision_Positive() = runTest {
         every { registry.requestDecision(testCert, any(), any()) } answers {
             registry.onUserDecision(testCert, true)
         }
-        assertTrue(runBlocking {
-            registry.check(testCert, true)
-        })
+        assertTrue(registry.check(testCert, true))
     }
 
     @Test
     fun testCheck_MultipleDecisionsForSameCert_Negative() {
+        // Keep runBlocking for complex concurrency test with Semaphore and threads
         val canSendFeedback = Semaphore(0)
         every { registry.requestDecision(testCert, any(), any()) } answers {
             thread {
@@ -104,6 +102,7 @@ class UserDecisionRegistryTest {
 
     @Test
     fun testCheck_MultipleDecisionsForSameCert_Positive() {
+        // Keep runBlocking for complex concurrency test with Semaphore and threads
         val canSendFeedback = Semaphore(0)
         every { registry.requestDecision(testCert, any(), any()) } answers {
             thread {
@@ -130,6 +129,7 @@ class UserDecisionRegistryTest {
 
     @Test
     fun testCheck_MultipleDecisionsForSameCert_cancel() {
+        // Keep runBlocking for complex concurrency test with Semaphore, threads, and job cancellation
         val canSendFeedback = Semaphore(0)
         val nm = mockk<NotificationManagerCompat>()
         every { nm.cancel(any(), any()) } just runs
@@ -160,12 +160,10 @@ class UserDecisionRegistryTest {
     }
 
     @Test
-    fun testCheck_UserDecisionImpossible() {
+    fun testCheck_UserDecisionImpossible() = runTest {
         every { NotificationUtils.notificationsPermitted(any()) } returns false
-        assertFalse(runBlocking {
-            // should return instantly
-            registry.check(testCert, false)
-        })
+        // should return instantly
+        assertFalse(registry.check(testCert, false))
         verify(inverse = true) {
             registry.requestDecision(any(), any(), any())
         }