diff --git a/autotests/test_builtin_effectloader.cpp b/autotests/test_builtin_effectloader.cpp
--- a/autotests/test_builtin_effectloader.cpp
+++ b/autotests/test_builtin_effectloader.cpp
@@ -400,6 +400,9 @@
         QCOMPARE(arguments.count(), 2);
         QCOMPARE(arguments.at(1).toString(), name);
     }
+
+    // Wait for effect->deleteLater() to be processed.
+    QTest::qWait(1);
 }
 
 void TestBuiltInEffectLoader::testLoadBuiltInEffect_data()
@@ -490,6 +493,9 @@
         QCOMPARE(arguments.count(), 2);
         QCOMPARE(arguments.at(1).toString(), name);
     }
+
+    // Wait for effect->deleteLater() to be processed.
+    QTest::qWait(1);
 }
 
 void TestBuiltInEffectLoader::testLoadAllEffects()