diff --git a/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/access/xtext/ui/JdtBasedConstructorScopeTest.java b/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/access/xtext/ui/JdtBasedConstructorScopeTest.java
index beaa5124d8f..2fba5a25b7e 100644
--- a/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/access/xtext/ui/JdtBasedConstructorScopeTest.java
+++ b/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/access/xtext/ui/JdtBasedConstructorScopeTest.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2009 itemis AG (http://www.itemis.eu) and others.
+ * Copyright (c) 2009, 2026 itemis AG (http://www.itemis.eu) and others.
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
  * http://www.eclipse.org/legal/epl-2.0.
@@ -32,6 +32,7 @@
 import com.google.common.base.Predicate;
 import com.google.common.base.Predicates;
 import com.google.common.collect.Iterables;
+import org.eclipse.xtext.testing.Flaky;
 
 /**
  * @author Sebastian Zarnekow - Initial contribution and API
@@ -75,6 +76,7 @@ public boolean apply(IEObjectDescription input) {
 		}));
 	}
 	
+	@Flaky
 	@Test public void testGetContents_03() {
 		assumeTrue(JavaCore.getPlugin().getBundle().getVersion().compareTo(new Version(3,31,0)) >= 0);
 		Iterable<IEObjectDescription> contents = constructorScope.getAllElements();
@@ -86,6 +88,7 @@ public boolean apply(IEObjectDescription input) {
 		}));
 	}
 	
+	@Flaky
 	@Test public void testGetContents_04() {
 		assumeTrue(JavaCore.getPlugin().getBundle().getVersion().compareTo(new Version(3,31,0)) >= 0);
 		Iterable<IEObjectDescription> contents = constructorScope.getAllElements();
diff --git a/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/access/xtext/ui/JdtBasedSimpleTypeScopeTest.java b/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/access/xtext/ui/JdtBasedSimpleTypeScopeTest.java
index 152e5f15070..0d3704e57a6 100644
--- a/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/access/xtext/ui/JdtBasedSimpleTypeScopeTest.java
+++ b/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/access/xtext/ui/JdtBasedSimpleTypeScopeTest.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2009 itemis AG (http://www.itemis.eu) and others.
+ * Copyright (c) 2009, 2026 itemis AG (http://www.itemis.eu) and others.
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
  * http://www.eclipse.org/legal/epl-2.0.
@@ -25,6 +25,7 @@
 import com.google.common.base.Predicate;
 import com.google.common.base.Predicates;
 import com.google.common.collect.Iterables;
+import org.eclipse.xtext.testing.Flaky;
 
 /**
  * @author Sebastian Zarnekow - Initial contribution and API
@@ -44,6 +45,7 @@ public void setUp() throws Exception {
 		typeScope = new JdtBasedSimpleTypeScope(factory.createTypeProvider(resourceSet), new IQualifiedNameConverter.DefaultImpl(),Predicates.<IEObjectDescription>alwaysTrue());
 	}
 	
+	@Flaky
 	@Test public void testGetContents_01() {
 		Iterable<IEObjectDescription> contents = typeScope.getAllElements();
 		assertTrue(Iterables.any(contents, new Predicate<IEObjectDescription>() {
@@ -64,6 +66,7 @@ public boolean apply(IEObjectDescription input) {
 		}));
 	}
 	
+	@Flaky
 	@Test public void testGetContents_03() {
 		Iterable<IEObjectDescription> contents = typeScope.getAllElements();
 		assertTrue(Iterables.any(contents, new Predicate<IEObjectDescription>() {
diff --git a/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/xtext/ui/ContentAssistTest.java b/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/xtext/ui/ContentAssistTest.java
index 81584cd7881..079f1478720 100644
--- a/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/xtext/ui/ContentAssistTest.java
+++ b/org.eclipse.xtext.common.types.eclipse.tests/tests/org/eclipse/xtext/common/types/xtext/ui/ContentAssistTest.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2010, 2022 itemis AG (http://www.itemis.eu) and others.
+ * Copyright (c) 2010, 2026 itemis AG (http://www.itemis.eu) and others.
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License 2.0 which is available at
  * http://www.eclipse.org/legal/epl-2.0.
@@ -21,6 +21,7 @@
 import org.eclipse.xtext.util.Modules2;
 import org.junit.BeforeClass;
 import org.junit.Test;
+import org.eclipse.xtext.testing.Flaky;
 
 import com.google.inject.Guice;
 import com.google.inject.Injector;
@@ -62,6 +63,7 @@ public Class<? extends IJavaProjectProvider> bindIJavaProjectProvider() {
 		};
 	}
 	
+	@Flaky
 	@Test
 	public void testDefaultArrayList_01() throws Exception {
 		//FIXME this does not consider JDT type filter, i.e. TypeFilter#isFiltered(char[],char[]) is not called.
@@ -70,6 +72,7 @@ public void testDefaultArrayList_01() throws Exception {
 		builder.assertText("java.lang.Appendable", "com.google.common.io.AppendableWriter");
 	}
 
+	@Flaky
 	@Test
 	public void testDefaultArrayList_02() throws Exception {
 		//FIXME this does not consider JDT type filter, i.e. TypeFilter#isFiltered(char[],char[]) is not called.
@@ -78,6 +81,7 @@ public void testDefaultArrayList_02() throws Exception {
 		builder.assertText("Appendable", "com.google.common.io.AppendableWriter");
 	}
 
+	@Flaky
 	@Test public void testCustomArrayList_01() throws Exception {
 		try {
 			newBuilder().append("custom ArrayLis").assertText(
@@ -105,6 +109,7 @@ public void testDefaultArrayList_02() throws Exception {
 		}
 	}
 	
+	@Flaky
 	@Test public void testCustomArrayList_02() throws Exception {
 		try {
 			newBuilder().append("import java.util.* custom ArrayLis").assertText(
@@ -134,54 +139,67 @@ public void testDefaultArrayList_02() throws Exception {
 		}
 	}
 	
+	@Flaky
 	@Test public void testDefaultBlockingQueue_01() throws Exception {
 		newBuilder().append("import java.util.* default BlockingQ").assertText("concurrent.BlockingQueue");
 	}
 	
+	@Flaky
 	@Test public void testDefaultBlockingQueue_02() throws Exception {
 		newBuilder().append("import java.* default BlockingQ").assertText("util.concurrent.BlockingQueue");
 	}
 	
+	@Flaky
 	@Test public void testCustomArrayList_03() throws Exception {
 		newBuilder().append("import java.util.* custom java.util.ArrayLis").assertText("ArrayList","ArrayList.ArrayListSpliterator");
 	}
 
+	@Flaky
 	@Test public void testCustomBlockingQueue_01() throws Exception {
 		newBuilder().append("import java.util.* custom BlockingQ").assertText("concurrent.BlockingQueue");
 	}
 	
+	@Flaky
 	@Test public void testCustomBlockingQueue_02() throws Exception {
 		newBuilder().append("import java.* custom BlockingQ").assertText("util.concurrent.BlockingQueue");
 	}
 	
+	@Flaky
 	@Test public void testCustomBlockingQueue_03() throws Exception {
 		newBuilder().append("import java.* custom concurrent.BlockingQ").assertText("util.concurrent.BlockingQueue");
 	}
 	
+	@Flaky
 	@Test public void testSubtypeArrayList_01() throws Exception {
 		newBuilder().append("subtype ArrayLis").assertText("java.util.ArrayList", "java.util.Arrays.ArrayList");
 	}
 	
+	@Flaky
 	@Test public void testSubtypeArrayList_02() throws Exception {
 		newBuilder().append("import java.util.* subtype ArrayLis").assertText("ArrayList", "Arrays.ArrayList");
 	}
 	
+	@Flaky
 	@Test public void testSubtypeHashSet_01() throws Exception {
 		newBuilder().append("subtype HashSe").assertText("java.util.HashSet");
 	}
 	
+	@Flaky
 	@Test public void testSubtypeHashSet_02() throws Exception {
 		newBuilder().append("import java.util.* subtype HashSe").assertText("HashSet");
 	}
 
+	@Flaky
 	@Test public void testSubtypeBlockingQueue_01() throws Exception {
 		newBuilder().append("import java.util.* subtype BlockingQ").assertText("concurrent.BlockingQueue");
 	}
 	
+	@Flaky
 	@Test public void testSubtypeBlockingQueue_02() throws Exception {
 		newBuilder().append("import java.* subtype BlockingQ").assertText("util.concurrent.BlockingQueue");
 	}
 	
+	@Flaky
 	@Test public void testSubtypeBlockingQueue_03() throws Exception {
 		newBuilder().append("import java.* subtype concurrent.BlockingQ").assertText("util.concurrent.BlockingQueue");
 	}
@@ -197,18 +215,21 @@ public void testDefaultArrayList_02() throws Exception {
 		}
 	}
 	
+	@Flaky
 	@Test public void testMap_01() throws Exception {
 		newBuilder().append("import java.util.* import javax.swing.text.html.* custom java.util.Map").assertText(
 				"java.util.Map");
 	}
 	
+	@Flaky
 	@Test public void testMap_02() throws Exception {
 		newBuilder().append("import javax.swing.text.html.* import java.util.* custom java.util.Map").assertText(
 				"java.util.Map");
 	}
 	
+	@Flaky
 	@Test public void testMap_03() throws Exception {
 		newBuilder().append("import java.util.* custom java.util.Map").assertText("Map");
 	}
 
-}
+ }