diff --git a/integration-test/build.gradle.kts b/integration-test/build.gradle.kts
index 997759f02..c310e6c47 100644
--- a/integration-test/build.gradle.kts
+++ b/integration-test/build.gradle.kts
@@ -119,8 +119,6 @@ spek2 {
 tasks {
     afterEvaluate {
         val runSpekJvmTest by getting(Test::class) {
-            // enable concurrent discovery
-            systemProperty("spek2.discovery.concurrent", "")
             filter {
                 includeTestsMatching("org.spekframework.spek2.*")
             }
diff --git a/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/Executor.kt b/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/Executor.kt
index e5c47272f..63b4a46e8 100644
--- a/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/Executor.kt
+++ b/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/Executor.kt
@@ -10,20 +10,29 @@ import org.spekframework.spek2.runtime.scope.ScopeImpl
 import org.spekframework.spek2.runtime.scope.TestScopeImpl
 import kotlin.coroutines.EmptyCoroutineContext
 
+interface TestHandle {
+    fun await()
+}
+
+expect class TestRunner(concurrency: Int) {
+    fun runTest(test: suspend () -> Unit): TestHandle
+}
+
 class Executor {
-    suspend fun execute(request: ExecutionRequest) {
+    fun execute(request: ExecutionRequest, concurrency: Int) {
+        val runner = TestRunner(concurrency)
         request.executionListener.executionStart()
-        // note that this call will be run in parallel depending on the CoroutineDispatcher used
-        supervisorScope {
-            request.roots.map { async { execute(it, request.executionListener) } }
-                .forEach { job ->
-                    try {
-                        job.await()
-                    } catch (e: Throwable) {
-                        println("An error has occurred: ${e.message}")
-                    }
+        request.roots
+            .map {
+                runner.runTest { execute(it, request.executionListener) }
+            }
+            .forEach { handle ->
+                try {
+                    handle.await()
+                } catch (e: Throwable) {
+                    println("An error has occurred: ${e.message}")
                 }
-        }
+            }
         request.executionListener.executionFinish()
     }
 
diff --git a/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/SpekRuntime.kt b/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/SpekRuntime.kt
index 0b2c161ef..0ad5dd296 100644
--- a/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/SpekRuntime.kt
+++ b/spek-runtime/src/commonMain/kotlin/org/spekframework/spek2/runtime/SpekRuntime.kt
@@ -65,13 +65,12 @@ class SpekRuntime {
 
     fun execute(request: ExecutionRequest) {
         doRunBlocking {
-            if (isConcurrentExecutionEnabled(false)) {
-                withContext(Dispatchers.Default) {
-                    Executor().execute(request)
-                }
+            val concurrency = if (isConcurrentExecutionEnabled(false)) {
+                getExecutionParallelism()
             } else {
-                Executor().execute(request)
+                1
             }
+            Executor().execute(request, concurrency)
         }
     }
 
@@ -113,6 +112,7 @@ class SpekRuntime {
 }
 
 expect fun isConcurrentDiscoveryEnabled(default: Boolean): Boolean
+expect fun getExecutionParallelism(): Int
 expect fun isConcurrentExecutionEnabled(default: Boolean): Boolean
 expect fun getGlobalTimeoutSetting(default: Long): Long
 
diff --git a/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/executors.kt b/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/executors.kt
index 16d989f4b..4ebd00bfa 100644
--- a/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/executors.kt
+++ b/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/executors.kt
@@ -2,9 +2,41 @@ package org.spekframework.spek2.runtime
 
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.runBlocking
+import java.util.concurrent.CompletableFuture
+import java.util.concurrent.ExecutionException
+import java.util.concurrent.Executors
 
 actual fun doRunBlocking(block: suspend CoroutineScope.() -> Unit) {
     runBlocking {
         block()
     }
 }
+
+actual class TestRunner actual constructor(concurrency: Int) {
+    private val executor = Executors.newFixedThreadPool(concurrency) { r ->
+        Thread(r).also {
+            it.isDaemon = true
+        }
+    }
+
+    actual fun runTest(test: suspend () -> Unit): TestHandle {
+        val handle = CompletableFuture<Unit>()
+
+        executor.submit {
+            runBlocking {
+                test()
+                handle.complete(null)
+            }
+        }
+
+        return object : TestHandle {
+            override fun await() {
+                try {
+                handle.get()
+                } catch (e: ExecutionException) {
+                    throw e.cause!!
+                }
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/timeout.kt b/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
index 57294ede0..855e47ddf 100644
--- a/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
+++ b/spek-runtime/src/jvmMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
@@ -22,4 +22,8 @@ actual fun isConcurrentExecutionEnabled(default: Boolean): Boolean {
 
 actual fun measureTime(block: () -> Unit): Long {
     return measureTimeMillis(block)
+}
+
+actual fun getExecutionParallelism(): Int {
+    return Runtime.getRuntime().availableProcessors()
 }
\ No newline at end of file
diff --git a/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/executors.kt b/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/executors.kt
index 16d989f4b..e56dc0e62 100644
--- a/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/executors.kt
+++ b/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/executors.kt
@@ -8,3 +8,17 @@ actual fun doRunBlocking(block: suspend CoroutineScope.() -> Unit) {
         block()
     }
 }
+
+actual class TestRunner actual constructor(concurrency: Int) {
+    actual fun runTest(test: suspend () -> Unit): TestHandle {
+        doRunBlocking {
+            test()
+        }
+
+        return object : TestHandle {
+            override fun await() {
+                // do nothing
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/timeout.kt b/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
index a67560958..34e289e74 100644
--- a/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
+++ b/spek-runtime/src/nativeMain/kotlin/org/spekframework/spek2/runtime/timeout.kt
@@ -19,4 +19,8 @@ actual fun isConcurrentExecutionEnabled(default: Boolean): Boolean {
 @UseExperimental(ExperimentalTime::class)
 actual fun measureTime(block: () -> Unit): Long {
     return MonoClock.measureTime(block).inMilliseconds.toLong()
+}
+
+actual fun getExecutionParallelism(): Int {
+    return 1
 }
\ No newline at end of file