diff --git a/test-framework/vertx/src/main/java/io/quarkus/test/vertx/DefaultUniAsserter.java b/test-framework/vertx/src/main/java/io/quarkus/test/vertx/DefaultUniAsserter.java
index 1820d442918cd..94d22af37c58a 100644
--- a/test-framework/vertx/src/main/java/io/quarkus/test/vertx/DefaultUniAsserter.java
+++ b/test-framework/vertx/src/main/java/io/quarkus/test/vertx/DefaultUniAsserter.java
@@ -148,17 +148,22 @@ public UniAsserter fail() {
         return this;
     }
 
+    @SuppressWarnings({ "unchecked", "rawtypes" })
     @Override
     public <T> UniAsserter assertFailedWith(Supplier<Uni<T>> uni, Consumer<Throwable> c) {
-        execution = uniFromSupplier(uni)
-                // return a new uni so we can avoid io.smallrye.mutiny.CompositeException
-                .onItemOrFailure().transformToUni((o, t) -> {
-                    if (t == null) {
-                        return Uni.createFrom().failure(() -> Assertions.fail("Uni did not contain a failure."));
-                    } else {
-                        return Uni.createFrom().item(() -> {
-                            c.accept(t);
-                            return null;
+        execution = execution.onItem()
+                .transformToUni((Function) new Function<Object, Uni<T>>() {
+                    @Override
+                    public Uni<T> apply(Object obj) {
+                        return uni.get().onItemOrFailure().transformToUni((o, t) -> {
+                            if (t == null) {
+                                return Uni.createFrom().failure(() -> Assertions.fail("Uni did not contain a failure."));
+                            } else {
+                                return Uni.createFrom().item(() -> {
+                                    c.accept(t);
+                                    return null;
+                                });
+                            }
                         });
                     }
                 });
diff --git a/test-framework/vertx/src/test/java/io/quarkus/test/vertx/UniAsserterTest.java b/test-framework/vertx/src/test/java/io/quarkus/test/vertx/UniAsserterTest.java
index 24be00e8bf0d8..2ddd35b4e4a44 100644
--- a/test-framework/vertx/src/test/java/io/quarkus/test/vertx/UniAsserterTest.java
+++ b/test-framework/vertx/src/test/java/io/quarkus/test/vertx/UniAsserterTest.java
@@ -1,12 +1,14 @@
 package io.quarkus.test.vertx;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.atomic.AtomicInteger;
 import java.util.function.Consumer;
+import java.util.function.Predicate;
 
 import org.junit.jupiter.api.Test;
 
@@ -56,12 +58,20 @@ public void testAssertFailedWith() {
         testAsserter(ua -> ua.assertFailedWith(() -> Uni.createFrom().failure(new NullPointerException()),
                 NullPointerException.class));
         testAsserterFailure(ua -> ua.assertFailedWith(() -> Uni.createFrom().failure(new IllegalStateException()),
-                NullPointerException.class));
+                NullPointerException.class), t -> AssertionError.class.isInstance(t));
+
+        // Note that assertFailedWith() is not tested at all because of the exception thrown from the previous assertEquals()
+        testAsserterFailure(ua -> ua.assertEquals(() -> Uni.createFrom().item("foo"), null)
+                .assertFailedWith(() -> Uni.createFrom().failure(new NullPointerException()),
+                        IllegalArgumentException.class),
+                t -> AssertionError.class.isInstance(t));
 
-        // TODO note that assertFailedWith() receives the exception thrown from the previous assertEquals()
-        testAsserter(ua -> ua.assertEquals(() -> Uni.createFrom().item("foo"), null)
+        testAsserterFailure(ua -> ua.assertTrue(() -> {
+            throw new IllegalArgumentException();
+        })
                 .assertFailedWith(() -> Uni.createFrom().failure(new NullPointerException()),
-                        AssertionError.class));
+                        IllegalArgumentException.class),
+                t -> IllegalArgumentException.class.isInstance(t));
     }
 
     @Test
@@ -180,6 +190,10 @@ private <T> void testAsserter(Consumer<UniAsserter> assertion, T finalItem) {
     }
 
     private void testAsserterFailure(Consumer<UniAsserter> assertion) {
+        testAsserterFailure(assertion, null);
+    }
+
+    private void testAsserterFailure(Consumer<UniAsserter> assertion, Predicate<Throwable> expected) {
         CompletableFuture<Object> cf = new CompletableFuture<>();
         DefaultUniAsserter asserter = new DefaultUniAsserter();
         assertion.accept(asserter);
@@ -188,7 +202,9 @@ private void testAsserterFailure(Consumer<UniAsserter> assertion) {
             cf.get();
             fail("No failure");
         } catch (ExecutionException e) {
-            // expected
+            if (expected != null) {
+                assertTrue(expected.test(e.getCause()));
+            }
         } catch (InterruptedException e) {
             throw new RuntimeException(e);
         }