diff --git a/tweed5/serde-extension/src/test/java/de/siphalor/tweed5/serde/extension/impl/ReadWriteExtensionImplTest.java b/tweed5/serde-extension/src/test/java/de/siphalor/tweed5/serde/extension/impl/ReadWriteExtensionImplTest.java
index d829452..a34e99d 100644
--- a/tweed5/serde-extension/src/test/java/de/siphalor/tweed5/serde/extension/impl/ReadWriteExtensionImplTest.java
+++ b/tweed5/serde-extension/src/test/java/de/siphalor/tweed5/serde/extension/impl/ReadWriteExtensionImplTest.java
@@ -3,16 +3,23 @@ package de.siphalor.tweed5.serde.extension.impl;
 import de.siphalor.tweed5.core.api.container.ConfigContainer;
 import de.siphalor.tweed5.core.api.entry.CollectionConfigEntry;
 import de.siphalor.tweed5.core.api.entry.CompoundConfigEntry;
+import de.siphalor.tweed5.core.api.entry.ConfigEntry;
+import de.siphalor.tweed5.core.api.entry.ConfigEntryValueVisitor;
+import de.siphalor.tweed5.core.api.entry.ConfigEntryVisitor;
+import de.siphalor.tweed5.core.api.entry.MutableStructuredConfigEntry;
 import de.siphalor.tweed5.core.api.entry.SimpleConfigEntry;
 import de.siphalor.tweed5.core.impl.DefaultConfigContainer;
 import de.siphalor.tweed5.core.impl.entry.CollectionConfigEntryImpl;
 import de.siphalor.tweed5.core.impl.entry.SimpleConfigEntryImpl;
 import de.siphalor.tweed5.core.impl.entry.StaticMapCompoundConfigEntryImpl;
+import de.siphalor.tweed5.patchwork.api.Patchwork;
 import de.siphalor.tweed5.serde.extension.api.ReadWriteExtension;
 import de.siphalor.tweed5.serde.hjson.HjsonLexer;
 import de.siphalor.tweed5.serde.hjson.HjsonReader;
 import de.siphalor.tweed5.serde.hjson.HjsonWriter;
 import de.siphalor.tweed5.serde_api.api.TweedDataVisitor;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -51,13 +58,21 @@ class ReadWriteExtensionImplTest {
 						.apply(entryReaderWriter(booleanReaderWriter()))
 		).apply(entryReaderWriter(collectionReaderWriter()));
 
+		MutableStructuredConfigEntry<Map<String, Integer>> mapEntry = new TestMapConfigEntry<>(
+				configContainer,
+				(Class<Map<String, Integer>>)(Class) Map.class,
+				new SimpleConfigEntryImpl<>(configContainer, Integer.class)
+						.apply(entryReaderWriter(intReaderWriter()))
+		).apply(entryReaderWriter(mutableStructuredReaderWriter()));
+
 		rootEntry = new StaticMapCompoundConfigEntryImpl<>(
 				configContainer,
 				((Class<Map<String, Object>>) (Class<?>) Map.class),
 				LinkedHashMap::new,
 				sequencedMap(List.of(
 						entry("int", intEntry),
-						entry("list", listEntry)
+						entry("list", listEntry),
+						entry("map", mapEntry)
 				))
 		).apply(entryReaderWriter(compoundReaderWriter()));
 
@@ -71,6 +86,7 @@ class ReadWriteExtensionImplTest {
 		Map<String, Object> value = new HashMap<>();
 		value.put("int", 123);
 		value.put("list", Arrays.asList(true, false, true));
+		value.put("map", sequencedMap(List.of(entry("a", 1), entry("b", 2))));
 
 		ReadWriteExtension readWriteExtension = configContainer.extension(ReadWriteExtension.class).orElseThrow();
 		assertDoesNotThrow(() -> readWriteExtension.write(
@@ -88,6 +104,10 @@ class ReadWriteExtensionImplTest {
 				\t\tfalse
 				\t\ttrue
 				\t]
+				\tmap: {
+				\t\ta: 1
+				\t\tb: 2
+				\t}
 				}
 				"""
 		);
@@ -105,6 +125,10 @@ class ReadWriteExtensionImplTest {
 						\t\tfalse
 						\t\ttrue
 						\t]
+						\tmap: {
+						\t\ta: 1
+						\t\tb: 2
+						\t}
 						}
 						"""))),
 				rootEntry,
@@ -115,7 +139,8 @@ class ReadWriteExtensionImplTest {
 		assertThat(result.hasValue()).isTrue();
 		assertThat(result.value()).isEqualTo(Map.of(
 				"int", 123,
-				"list", Arrays.asList(true, false, true)
+				"list", Arrays.asList(true, false, true),
+				"map", Map.of("a", 1, "b", 2)
 		));
 	}
 
diff --git a/tweed5/serde-extension/src/test/java/de/siphalor/tweed5/serde/extension/impl/TestMapConfigEntry.java b/tweed5/serde-extension/src/test/java/de/siphalor/tweed5/serde/extension/impl/TestMapConfigEntry.java
new file mode 100644
index 0000000..eed508f
--- /dev/null
+++ b/tweed5/serde-extension/src/test/java/de/siphalor/tweed5/serde/extension/impl/TestMapConfigEntry.java
@@ -0,0 +1,87 @@
+package de.siphalor.tweed5.serde.extension.impl;
+
+import de.siphalor.tweed5.core.api.Arity;
+import de.siphalor.tweed5.core.api.container.ConfigContainer;
+import de.siphalor.tweed5.core.api.entry.BaseConfigEntry;
+import de.siphalor.tweed5.core.api.entry.ConfigEntry;
+import de.siphalor.tweed5.core.api.entry.ConfigEntryValueVisitor;
+import de.siphalor.tweed5.core.api.entry.ConfigEntryVisitor;
+import de.siphalor.tweed5.core.api.entry.MutableStructuredConfigEntry;
+import de.siphalor.tweed5.core.api.entry.SubEntryKey;
+import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+public class TestMapConfigEntry<V>
+		extends BaseConfigEntry<Map<String, V>>
+		implements MutableStructuredConfigEntry<Map<String, V>> {
+	private final ConfigEntry<V> valueEntry;
+
+	public TestMapConfigEntry(
+			ConfigContainer<?> container,
+			Class<Map<String, V>> valueClass,
+			ConfigEntry<V> valueEntry
+	) {
+		super(container, valueClass);
+		this.valueEntry = valueEntry;
+	}
+
+	@Override
+	public @NonNull Map<String, V> instantiateValue() {
+		return new LinkedHashMap<>();
+	}
+
+	@Override
+	public void set(Map<String, V> value, String dataKey, Object subValue) {
+		value.put(dataKey, (V) subValue);
+	}
+
+	@Override
+	public @Nullable ConfigEntry<?> getEntry(String dataKey) {
+		return valueEntry;
+	}
+
+	@Override
+	public Object get(Map<String, V> value, String dataKey) {
+		return value.get(dataKey);
+	}
+
+	@Override
+	public Map<String, ConfigEntry<?>> subEntries() {
+		return Map.of(":value", valueEntry);
+	}
+
+	@Override
+	public void visitInOrder(ConfigEntryVisitor visitor) {
+		if (visitor.enterStructuredEntry(this)) {
+			if (visitor.enterStructuredSubEntry(":value", Arity.ANY)) {
+				valueEntry.visitInOrder(visitor);
+				visitor.leaveStructuredSubEntry(":value", Arity.ANY);
+			}
+			visitor.leaveStructuredEntry(this);
+		}
+	}
+
+	@Override
+	public void visitInOrder(ConfigEntryValueVisitor visitor, Map<String, V> value) {
+		if (visitor.enterStructuredEntry(this, value)) {
+			value.forEach((key, subValue) -> {
+				SubEntryKey subEntryKey = SubEntryKey.addressable(":value", key, key);
+				if (visitor.enterSubEntry(subEntryKey)) {
+					valueEntry.visitInOrder(visitor, subValue);
+					visitor.leaveSubEntry(subEntryKey);
+				}
+			});
+			visitor.leaveStructuredEntry(this, value);
+		}
+	}
+
+	@Override
+	public Map<String, V> deepCopy(Map<String, V> value) {
+		Map<String, V> copy = instantiateValue();
+		value.forEach((key, subValue) -> copy.put(key, valueEntry.deepCopy(subValue)));
+		return copy;
+	}
+}