diff --git a/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/JUnit5Context.java b/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/JUnit5Context.java
index 069d0dc780b..bd6d44942dc 100644
--- a/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/JUnit5Context.java
+++ b/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/JUnit5Context.java
@@ -10,56 +10,103 @@
 
 package org.junit.gen5.engine.junit5;
 
-import java.util.HashMap;
-import java.util.Map;
-
 import org.junit.gen5.engine.Context;
 import org.junit.gen5.engine.junit5.execution.TestExtensionRegistry;
 
 public class JUnit5Context implements Context {
 
-	private final Map<String, Object> map;
+	private final State state;
 
 	public JUnit5Context() {
-		this(new HashMap<>());
+		this(new State());
 	}
 
-	private JUnit5Context(Map<String, Object> map) {
-		this.map = map;
+	private JUnit5Context(State state) {
+		this.state = state;
 	}
 
-	public JUnit5Context withTestInstanceProvider(TestInstanceProvider testInstanceProvider) {
-		return with(TestInstanceProvider.class.getName(), testInstanceProvider);
+	public TestInstanceProvider getTestInstanceProvider() {
+		return state.testInstanceProvider;
 	}
 
-	public TestInstanceProvider getTestInstanceProvider() {
-		return get(TestInstanceProvider.class.getName(), TestInstanceProvider.class);
+	public BeforeEachCallback getBeforeEachCallback() {
+		return state.beforeEachCallback;
 	}
 
-	public JUnit5Context withBeforeEachCallback(BeforeEachCallback beforeEachCallback) {
-		return with("beforeEachCallback", beforeEachCallback);
+	public TestExtensionRegistry getTestExtensionRegistry() {
+		return state.testExtensionRegistry;
 	}
 
-	public BeforeEachCallback getBeforeEachCallback() {
-		return get("beforeEachCallback", BeforeEachCallback.class);
+	public Builder extend() {
+		return builder(this);
 	}
 
-	public JUnit5Context withTestExtensionRegistry(TestExtensionRegistry testExtensionRegistry) {
-		return with("testExtensionRegistry", testExtensionRegistry);
+	public static Builder builder() {
+		return new Builder(null, new State());
 	}
 
-	public TestExtensionRegistry getTestExtensionRegistry() {
-		return get("testExtensionRegistry", TestExtensionRegistry.class);
+	public static Builder builder(JUnit5Context context) {
+		return new Builder(context.state, null);
 	}
 
-	private JUnit5Context with(String key, Object value) {
-		Map<String, Object> newMap = new HashMap<>(map);
-		newMap.put(key, value);
-		return new JUnit5Context(newMap);
+	private static final class State implements Cloneable {
+
+		TestInstanceProvider testInstanceProvider;
+		BeforeEachCallback beforeEachCallback;
+		TestExtensionRegistry testExtensionRegistry;
+
+		@Override
+		public State clone() {
+			try {
+				return (State) super.clone();
+			}
+			catch (CloneNotSupportedException e) {
+				throw new RuntimeException("State could not be cloned", e);
+			}
+		}
+
 	}
 
-	private <T> T get(String key, Class<T> clazz) {
-		return clazz.cast(map.get(key));
+	public static class Builder {
+
+		private State originalState;
+		private State newState;
+
+		private Builder(State originalState, State state) {
+			this.originalState = originalState;
+			this.newState = state;
+		}
+
+		public Builder withTestInstanceProvider(TestInstanceProvider testInstanceProvider) {
+			newState().testInstanceProvider = testInstanceProvider;
+			return this;
+		}
+
+		public Builder withBeforeEachCallback(BeforeEachCallback beforeEachCallback) {
+			newState().beforeEachCallback = beforeEachCallback;
+			return this;
+		}
+
+		public Builder withTestExtensionRegistry(TestExtensionRegistry testExtensionRegistry) {
+			newState().testExtensionRegistry = testExtensionRegistry;
+			return this;
+		}
+
+		public JUnit5Context build() {
+			if (newState != null) {
+				originalState = newState;
+				newState = null;
+			}
+			return new JUnit5Context(originalState);
+		}
+
+		private State newState() {
+			if (newState == null) {
+				this.newState = originalState.clone();
+			}
+			return newState;
+		}
+
 	}
 
 }
diff --git a/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/ClassTestDescriptor.java b/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/ClassTestDescriptor.java
index 20875dfd6f7..5ffff1347e2 100644
--- a/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/ClassTestDescriptor.java
+++ b/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/ClassTestDescriptor.java
@@ -79,10 +79,11 @@ public boolean isContainer() {
 	@Override
 	public JUnit5Context beforeAll(JUnit5Context context) {
 		// @formatter:off
-		return context
+		return context.extend()
 				.withTestInstanceProvider(testInstanceProvider(context))
 				.withBeforeEachCallback(beforeEachCallback(context))
-				.withTestExtensionRegistry(populateNewTestExtensionRegistryFromExtendWith(testClass, context.getTestExtensionRegistry()));
+				.withTestExtensionRegistry(populateNewTestExtensionRegistryFromExtendWith(testClass, context.getTestExtensionRegistry()))
+				.build();
 		// @formatter:on
 	}
 
diff --git a/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/JUnit5EngineDescriptor.java b/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/JUnit5EngineDescriptor.java
index 0070ef9e565..b8b843ade5a 100644
--- a/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/JUnit5EngineDescriptor.java
+++ b/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/JUnit5EngineDescriptor.java
@@ -24,7 +24,7 @@ public JUnit5EngineDescriptor(TestEngine engine) {
 
 	@Override
 	public JUnit5Context beforeAll(JUnit5Context context) {
-		return context.withTestExtensionRegistry(new TestExtensionRegistry());
+		return context.extend().withTestExtensionRegistry(new TestExtensionRegistry()).build();
 	}
 
 }
diff --git a/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/MethodTestDescriptor.java b/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/MethodTestDescriptor.java
index 840b87c0c23..add91f4c903 100644
--- a/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/MethodTestDescriptor.java
+++ b/junit5-engine/src/main/java/org/junit/gen5/engine/junit5/descriptor/MethodTestDescriptor.java
@@ -87,8 +87,8 @@ public boolean isContainer() {
 
 	@Override
 	public JUnit5Context execute(JUnit5Context context) throws Throwable {
-		JUnit5Context myContext = context.withTestExtensionRegistry(
-			populateNewTestExtensionRegistryFromExtendWith(testMethod, context.getTestExtensionRegistry()));
+		JUnit5Context myContext = context.extend().withTestExtensionRegistry(
+			populateNewTestExtensionRegistryFromExtendWith(testMethod, context.getTestExtensionRegistry())).build();
 
 		TestInstanceProvider provider = context.getTestInstanceProvider();
 		Object testInstance = provider.getTestInstance();