diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphConcatSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphConcatSpec.scala
index bea3be6b91..babee44add 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphConcatSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/GraphConcatSpec.scala
@@ -102,14 +102,17 @@ class GraphConcatSpec extends TwoStreamsSetup {
       subscriber1.expectSubscriptionAndError(TestException)
 
       val subscriber2 = setup(nonemptyPublisher(1 to 4), failedPublisher)
-      subscriber2.expectSubscriptionAndError(TestException)
+      subscriber2.expectSubscription().request(5)
+
+      var errorSignalled = false
+      if (!errorSignalled) errorSignalled ||= subscriber2.expectNextOrError(1, TestException).isLeft
+      if (!errorSignalled) errorSignalled ||= subscriber2.expectNextOrError(2, TestException).isLeft
+      if (!errorSignalled) errorSignalled ||= subscriber2.expectNextOrError(3, TestException).isLeft
+      if (!errorSignalled) errorSignalled ||= subscriber2.expectNextOrError(4, TestException).isLeft
+      if (!errorSignalled) subscriber2.expectError(TestException)
     }
 
     "work with one nonempty and one delayed failed publisher" in assertAllStagesStopped {
-      // This test and the next one are materialization order dependent and rely on the fact
-      // that there are only 3 submodules in the graph that gets created and that an immutable
-      // set (what they are stored in internally) of size 4 or less is an optimized version that
-      // traverses in insertion order
       val subscriber = setup(nonemptyPublisher(1 to 4), soonToFailPublisher)
       subscriber.expectSubscription().request(5)
 
@@ -118,23 +121,12 @@ class GraphConcatSpec extends TwoStreamsSetup {
       if (!errorSignalled) errorSignalled ||= subscriber.expectNextOrError(2, TestException).isLeft
       if (!errorSignalled) errorSignalled ||= subscriber.expectNextOrError(3, TestException).isLeft
       if (!errorSignalled) errorSignalled ||= subscriber.expectNextOrError(4, TestException).isLeft
-      if (!errorSignalled) subscriber.expectSubscriptionAndError(TestException)
+      if (!errorSignalled) subscriber.expectError(TestException)
     }
 
     "work with one delayed failed and one nonempty publisher" in assertAllStagesStopped {
-      // This test and the previous one are materialization order dependent and rely on the fact
-      // that there are only 3 submodules in the graph that gets created and that an immutable
-      // set (what they are stored in internally) of size 4 or less is an optimized version that
-      // traverses in insertion order
       val subscriber = setup(soonToFailPublisher, nonemptyPublisher(1 to 4))
-      subscriber.expectSubscription().request(5)
-
-      var errorSignalled = false
-      if (!errorSignalled) errorSignalled ||= subscriber.expectNextOrError(1, TestException).isLeft
-      if (!errorSignalled) errorSignalled ||= subscriber.expectNextOrError(2, TestException).isLeft
-      if (!errorSignalled) errorSignalled ||= subscriber.expectNextOrError(3, TestException).isLeft
-      if (!errorSignalled) errorSignalled ||= subscriber.expectNextOrError(4, TestException).isLeft
-      if (!errorSignalled) subscriber.expectSubscriptionAndError(TestException)
+      subscriber.expectSubscriptionAndError(TestException)
     }
 
     "correctly handle async errors in secondary upstream" in assertAllStagesStopped {