diff --git a/CLAUDE.md b/CLAUDE.md
index 75ec8a6..4d373b0 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -27,17 +27,19 @@ mvn generate-sources
 
 **Note:** Tests run with `-Duser.timezone=Europe/Oslo` (configured in surefire plugin).
 
+**Note:** Surefire runs tests on the module path because `module-info.java` exists.
+
 ## Architecture
 
 ### Code Generation (bulk of the codebase)
 
 The `cxf-xjc-plugin` generates ~1,900 Java classes from XSD schemas during `generate-sources`:
-- **SIRI 2.0** XSDs → `uk.org.siri.siri20.*` (plus `uk.org.ifopt.siri20`, `uk.org.acbs.siri20`, `eu.datex2.siri20`)
-- **SIRI 2.1** XSDs → `uk.org.siri.siri21.*` (plus `uk.org.ifopt.siri21`, `uk.org.acbs.siri21`, `eu.datex2.siri21`)
+- **SIRI 2.0** XSDs → `org.entur.siri.schema.v20.siri` (plus `.ifopt`, `.acsb`, `.datex2`)
+- **SIRI 2.1** XSDs → `org.entur.siri.schema.v21.siri` (plus `.ifopt`, `.acsb`, `.datex2`, `.gml`)
 
 Generated sources land in `target/generated-sources`. JAXB binding customizations are in `src/main/resources/siri-{2.0,2.1}/xjb/jaxb-bindings.xml` — these map `xsd:dateTime`/`xsd:time` to `java.time.ZonedDateTime` and `xsd:duration` to `java.time.Duration`.
 
-### Handwritten Code (~9 files)
+### Handwritten Code (~11 files)
 
 | Package | Class | Purpose |
 |---------|-------|---------|
@@ -47,16 +49,18 @@ Generated sources land in `target/generated-sources`. JAXB binding customization
 | `org.entur.siri.validator` | `SiriValidationEventHandler` | Collects validation errors |
 | `org.entur.siri21.util` | `SiriXml` | SIRI 2.1 XML marshalling/unmarshalling (JAXB) |
 | `org.entur.siri21.util` | `SiriJson` | SIRI 2.1 JSON conversion (Jackson + Jakarta XML Bind) |
-| `org.rutebanken.siri20.util` | `SiriXml` | SIRI 2.0 XML marshalling/unmarshalling (legacy package) |
+| `org.entur.siri20.util` | `SiriXml` | SIRI 2.0 XML marshalling/unmarshalling |
+| `org.entur.siri20.util` | `SiriJson` | SIRI 2.0 JSON conversion (Jackson + Jakarta XML Bind) |
 | `org.entur.siri` | `UnsupportedSiriVersionException` | Exception for unsupported SIRI versions |
+| (module root) | `module-info.java` | JPMS descriptor: `open module org.entur.siri` |
 
 ### Key Design Decisions
 
 - **Jakarta EE**: Uses `jakarta.xml.bind` (3.0+), not legacy `javax.xml.bind`.
 - **Java 11** target (source and bytecode) via `<release>` in the compiler plugin; CI builds on JDK 25, and any JDK from 11 to 25 works locally.
+- **JPMS**: `src/main/java/module-info.java` declares `open module org.entur.siri` (open because the consumer's JAXB runtime needs reflective access). When you add a generated or handwritten package, add an `exports` line for it.
+- **No `NamespacePrefixMapper` in the API**: `SiriXml.toXml` takes a `Consumer<Marshaller>` customizer. The `JAXBNamespacePrefixMapper` stub shares a package with the JAXB RI, so it cannot be used on the module path.
 - **JUnit 4** for tests.
-- **JSON support exists only for SIRI 2.1** (`SiriJson`), not 2.0.
-- **SIRI 2.0 utility lives in legacy package** `org.rutebanken.siri20.util` (historical).
 
 ### Test Data
 
diff --git a/README.md b/README.md
index 9f45435..c74afc6 100644
--- a/README.md
+++ b/README.md
@@ -11,4 +11,56 @@ Source 1.0 - 1.4 http://user47094.vs.easily.co.uk/siri/
 
 Source 2.0 -> https://www.vdv.de/siri.aspx 
 
-Also provides XML-validation through method `SiriValidator.validate`.
\ No newline at end of file
+Also provides XML-validation through method `SiriValidator.validate`.
+
+## Java modules (JPMS)
+
+The jar is a named module, `org.entur.siri`. It is an `open module`, because the JAXB runtime that you supply needs reflective access to the generated classes. It requires `jakarta.xml.bind` and Jackson. You must also provide a JAXB implementation, for example `com.sun.xml.bind:jaxb-impl`.
+
+```java
+module my.app {
+    requires org.entur.siri;
+}
+```
+
+## Upgrading to 3.0
+
+**Breaking change: the generated packages are renamed.**
+The XML namespaces and the wire format are unchanged. Update your imports:
+
+| Before | After |
+|---|---|
+| `uk.org.siri.siri20` / `siri21` | `org.entur.siri.schema.v20.siri` / `v21.siri` |
+| `uk.org.ifopt.siri20` / `siri21` | `org.entur.siri.schema.v20.ifopt` / `v21.ifopt` |
+| `uk.org.acbs.siri20` / `siri21` | `org.entur.siri.schema.v20.acsb` / `v21.acsb` |
+| `eu.datex2.siri20.schema._2_0rc1._2_0` / `siri21...` | `org.entur.siri.schema.v20.datex2` / `v21.datex2` |
+| `net.opengis.gml.siri` | `org.entur.siri.schema.v21.gml` |
+
+
+**Breaking change: `NamespacePrefixMapper` is removed from `SiriXml`.**
+The overloads `toXml(Siri, NamespacePrefixMapper)` and `toXml(Siri, NamespacePrefixMapper, OutputStream)` in `org.entur.siri21.util.SiriXml` and `org.entur.siri20.util.SiriXml` now take a `Consumer<Marshaller>` instead. The `JAXBNamespacePrefixMapper` dependency is removed, because it shares a package with the JAXB reference implementation and cannot be used on the module path.
+
+Before:
+
+```java
+SiriXml.toXml(siri, myNamespacePrefixMapper);
+```
+
+After: set the property of your own JAXB implementation on the marshaller.
+
+```java
+SiriXml.toXml(siri, marshaller -> {
+    try {
+        marshaller.setProperty("org.glassfish.jaxb.namespacePrefixMapper", myNamespacePrefixMapper);
+    } catch (PropertyException e) {
+        throw new IllegalStateException(e);
+    }
+});
+```
+
+The property name depends on your JAXB implementation. Use the one that your implementation documents. If your own code imports `com.sun.xml.bind.marshaller.NamespacePrefixMapper`, add the dependency that provides it yourself. This library no longer brings it in.
+
+**Breaking change: the SIRI 2.0 utility package is renamed.**
+`org.rutebanken.siri20.util` (`SiriXml`, `SiriJson`) is now `org.entur.siri20.util`, which matches `org.entur.siri21.util`. Update your imports. There are no deprecated forwarders in the old package.
+
+The module name is now explicit (`org.entur.siri`). It was derived from the jar file name (`siri.java.model`) before.
diff --git a/pom.xml b/pom.xml
index eb78e0a..df5e6f5 100644
--- a/pom.xml
+++ b/pom.xml
@@ -24,9 +24,7 @@
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
         <jdk.version>11</jdk.version>
-        <slf4j.version>2.0.9</slf4j.version>
         <jackson.version>2.18.11</jackson.version>
-        <slf4j.version>2.0.7</slf4j.version>
         <jreleaser-maven-plugin.version>1.18.0</jreleaser-maven-plugin.version>
         <cxf-xjc-plugin.version>4.2.0</cxf-xjc-plugin.version>
         <maven-javadoc-plugin.version>3.11.2</maven-javadoc-plugin.version>
@@ -71,11 +69,6 @@
     </organization>
 
     <dependencies>
-        <dependency>
-            <groupId>com.googlecode.jaxb-namespaceprefixmapper-interfaces</groupId>
-            <artifactId>JAXBNamespacePrefixMapper</artifactId>
-            <version>6.1.0</version>
-        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>
@@ -90,6 +83,12 @@
             <groupId>com.fasterxml.jackson.module</groupId>
             <artifactId>jackson-module-jakarta-xmlbind-annotations</artifactId>
             <version>${jackson.version}</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>jakarta.activation</groupId>
+                    <artifactId>jakarta.activation-api</artifactId>
+                </exclusion>
+            </exclusions>
         </dependency>
         <dependency>
             <groupId>jakarta.xml.bind</groupId>
@@ -108,17 +107,6 @@
             <version>3.0.2</version>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>jakarta.activation</groupId>
-            <artifactId>jakarta.activation-api</artifactId>
-            <scope>test</scope>
-            <version>2.1.0</version>
-        </dependency>
-        <dependency>
-            <groupId>org.slf4j</groupId>
-            <artifactId>slf4j-api</artifactId>
-            <version>${slf4j.version}</version>
-        </dependency>
         <!-- Test -->
         <dependency>
             <groupId>junit</groupId>
@@ -126,12 +114,6 @@
             <version>4.13.2</version>
             <scope>test</scope>
         </dependency>
-        <dependency>
-            <groupId>org.slf4j</groupId>
-            <artifactId>slf4j-simple</artifactId>
-            <version>${slf4j.version}</version>
-            <scope>test</scope>
-        </dependency>
     </dependencies>
 
     <build>
diff --git a/src/main/java/module-info.java b/src/main/java/module-info.java
new file mode 100644
index 0000000..4f144d3
--- /dev/null
+++ b/src/main/java/module-info.java
@@ -0,0 +1,21 @@
+open module org.entur.siri {
+    requires transitive jakarta.xml.bind;
+    requires com.fasterxml.jackson.annotation;
+    requires com.fasterxml.jackson.databind;
+    requires com.fasterxml.jackson.module.jakarta.xmlbind;
+
+    exports org.entur.siri;
+    exports org.entur.siri.adapter;
+    exports org.entur.siri.validator;
+    exports org.entur.siri21.util;
+    exports org.entur.siri20.util;
+    exports org.entur.siri.schema.v20.acsb;
+    exports org.entur.siri.schema.v20.datex2;
+    exports org.entur.siri.schema.v20.ifopt;
+    exports org.entur.siri.schema.v20.siri;
+    exports org.entur.siri.schema.v21.acsb;
+    exports org.entur.siri.schema.v21.datex2;
+    exports org.entur.siri.schema.v21.gml;
+    exports org.entur.siri.schema.v21.ifopt;
+    exports org.entur.siri.schema.v21.siri;
+}
diff --git a/src/main/java/org/entur/siri/adapter/ZonedDateTimeDateTimeXmlAdapter.java b/src/main/java/org/entur/siri/adapter/ZonedDateTimeDateTimeXmlAdapter.java
new file mode 100644
index 0000000..e69de29
diff --git a/src/main/java/org/entur/siri/adapter/ZonedDateTimeTimeXmlAdapter.java b/src/main/java/org/entur/siri/adapter/ZonedDateTimeTimeXmlAdapter.java
new file mode 100644
index 0000000..e69de29
diff --git a/src/main/java/org/entur/siri/adapter/ZonedDateTimeXmlAdapter.java b/src/main/java/org/entur/siri/adapter/ZonedDateTimeXmlAdapter.java
new file mode 100644
index 0000000..878facd
--- /dev/null
+++ b/src/main/java/org/entur/siri/adapter/ZonedDateTimeXmlAdapter.java
@@ -0,0 +1,22 @@
+package org.entur.siri.adapter;
+
+import jakarta.xml.bind.annotation.adapters.XmlAdapter;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+
+/**
+ * JAXB adapter for {@code xsd:dateTime} bound to {@link ZonedDateTime}. Written by hand so that XJC does not
+ * generate an adapter class into the {@code org.w3._2001.xmlschema} package, which would be a split package.
+ */
+public class ZonedDateTimeXmlAdapter extends XmlAdapter<String, ZonedDateTime> {
+
+    @Override
+    public ZonedDateTime unmarshal(String value) {
+        return ZonedDateTimeAdapter.parse(value);
+    }
+
+    @Override
+    public String marshal(ZonedDateTime value) {
+        return DateTimeFormatter.ISO_OFFSET_DATE_TIME.format(value);
+    }
+}
diff --git a/src/main/java/org/entur/siri/adapter/ZonedTimeXmlAdapter.java b/src/main/java/org/entur/siri/adapter/ZonedTimeXmlAdapter.java
new file mode 100644
index 0000000..a318f6c
--- /dev/null
+++ b/src/main/java/org/entur/siri/adapter/ZonedTimeXmlAdapter.java
@@ -0,0 +1,22 @@
+package org.entur.siri.adapter;
+
+import jakarta.xml.bind.annotation.adapters.XmlAdapter;
+import java.time.ZonedDateTime;
+import java.time.format.DateTimeFormatter;
+
+/**
+ * JAXB adapter for {@code xsd:time} bound to {@link ZonedDateTime}. Written by hand so that XJC does not
+ * generate an adapter class into the {@code org.w3._2001.xmlschema} package, which would be a split package.
+ */
+public class ZonedTimeXmlAdapter extends XmlAdapter<String, ZonedDateTime> {
+
+    @Override
+    public ZonedDateTime unmarshal(String value) {
+        return ZonedDateTimeAdapter.parse(value);
+    }
+
+    @Override
+    public String marshal(ZonedDateTime value) {
+        return DateTimeFormatter.ISO_OFFSET_TIME.format(value);
+    }
+}
diff --git a/src/main/java/org/entur/siri/validator/SiriValidator.java b/src/main/java/org/entur/siri/validator/SiriValidator.java
index 42d1fc1..bece60e 100644
--- a/src/main/java/org/entur/siri/validator/SiriValidator.java
+++ b/src/main/java/org/entur/siri/validator/SiriValidator.java
@@ -51,10 +51,10 @@ public class SiriValidator {
 
     private static void init() throws JAXBException {
         if (siri20jaxbContext == null) {
-            siri20jaxbContext = JAXBContext.newInstance(uk.org.siri.siri20.Siri.class);
+            siri20jaxbContext = JAXBContext.newInstance(org.entur.siri.schema.v20.siri.Siri.class);
         }
         if (siri21jaxbContext == null) {
-            siri21jaxbContext = JAXBContext.newInstance(uk.org.siri.siri21.Siri.class);
+            siri21jaxbContext = JAXBContext.newInstance(org.entur.siri.schema.v21.siri.Siri.class);
         }
     }
     /**
diff --git a/src/main/java/org/rutebanken/siri20/util/SiriJson.java b/src/main/java/org/entur/siri20/util/SiriJson.java
similarity index 97%
rename from src/main/java/org/rutebanken/siri20/util/SiriJson.java
rename to src/main/java/org/entur/siri20/util/SiriJson.java
index 9127181..d2b0304 100644
--- a/src/main/java/org/rutebanken/siri20/util/SiriJson.java
+++ b/src/main/java/org/entur/siri20/util/SiriJson.java
@@ -13,7 +13,7 @@
  * limitations under the Licence.
  */
 
-package org.rutebanken.siri20.util;
+package org.entur.siri20.util;
 
 import com.fasterxml.jackson.annotation.JsonInclude;
 import com.fasterxml.jackson.databind.DeserializationFeature;
@@ -23,7 +23,7 @@
 import com.fasterxml.jackson.databind.type.TypeFactory;
 import com.fasterxml.jackson.databind.util.StdDateFormat;
 import com.fasterxml.jackson.module.jakarta.xmlbind.JakartaXmlBindAnnotationIntrospector;
-import uk.org.siri.siri20.Siri;
+import org.entur.siri.schema.v20.siri.Siri;
 
 import java.io.IOException;
 import java.io.OutputStream;
diff --git a/src/main/java/org/rutebanken/siri20/util/SiriXml.java b/src/main/java/org/entur/siri20/util/SiriXml.java
similarity index 79%
rename from src/main/java/org/rutebanken/siri20/util/SiriXml.java
rename to src/main/java/org/entur/siri20/util/SiriXml.java
index 538529f..dc54d94 100644
--- a/src/main/java/org/rutebanken/siri20/util/SiriXml.java
+++ b/src/main/java/org/entur/siri20/util/SiriXml.java
@@ -13,13 +13,14 @@
  * limitations under the Licence.
  */
 
-package org.rutebanken.siri20.util;
+package org.entur.siri20.util;
 
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.StringReader;
 import java.io.StringWriter;
+import java.util.function.Consumer;
 
 import jakarta.xml.bind.JAXBContext;
 import jakarta.xml.bind.JAXBException;
@@ -29,10 +30,9 @@
 import javax.xml.stream.XMLStreamException;
 import javax.xml.stream.XMLStreamReader;
 
-import com.sun.xml.bind.marshaller.NamespacePrefixMapper;
 
 import org.entur.siri.XmlInputFactoryProvider;
-import uk.org.siri.siri20.Siri;
+import org.entur.siri.schema.v20.siri.Siri;
 
 public class SiriXml {
 
@@ -73,12 +73,12 @@ public static String toXml(Siri siri) throws JAXBException {
         return toXml(siri, null);
     }
 
-    public static String toXml(Siri siri, NamespacePrefixMapper customNamespacePrefixMapper) throws JAXBException {
+    public static String toXml(Siri siri, Consumer<Marshaller> marshallerCustomizer) throws JAXBException {
 
         Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
 
-        if (customNamespacePrefixMapper != null) {
-            jaxbMarshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", customNamespacePrefixMapper);
+        if (marshallerCustomizer != null) {
+            marshallerCustomizer.accept(jaxbMarshaller);
         }
         StringWriter sw = new StringWriter();
         jaxbMarshaller.marshal(siri, sw);
@@ -86,11 +86,11 @@ public static String toXml(Siri siri, NamespacePrefixMapper customNamespacePrefi
         return sw.toString();
     }
 
-    public static void toXml(Siri siri, NamespacePrefixMapper customNamespacePrefixMapper, OutputStream out) throws JAXBException, IOException {
+    public static void toXml(Siri siri, Consumer<Marshaller> marshallerCustomizer, OutputStream out) throws JAXBException, IOException {
         Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
 
-        if (customNamespacePrefixMapper != null) {
-            jaxbMarshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", customNamespacePrefixMapper);
+        if (marshallerCustomizer != null) {
+            marshallerCustomizer.accept(jaxbMarshaller);
         }
         jaxbMarshaller.marshal(siri, out);
     }
diff --git a/src/main/java/org/entur/siri21/util/SiriJson.java b/src/main/java/org/entur/siri21/util/SiriJson.java
index 23ff35d..eda3976 100644
--- a/src/main/java/org/entur/siri21/util/SiriJson.java
+++ b/src/main/java/org/entur/siri21/util/SiriJson.java
@@ -23,7 +23,7 @@
 import com.fasterxml.jackson.databind.type.TypeFactory;
 import com.fasterxml.jackson.databind.util.StdDateFormat;
 import com.fasterxml.jackson.module.jakarta.xmlbind.JakartaXmlBindAnnotationIntrospector;
-import uk.org.siri.siri21.Siri;
+import org.entur.siri.schema.v21.siri.Siri;
 
 import java.io.IOException;
 import java.io.OutputStream;
diff --git a/src/main/java/org/entur/siri21/util/SiriXml.java b/src/main/java/org/entur/siri21/util/SiriXml.java
index 41c3f46..92293ca 100644
--- a/src/main/java/org/entur/siri21/util/SiriXml.java
+++ b/src/main/java/org/entur/siri21/util/SiriXml.java
@@ -15,9 +15,8 @@
 
 package org.entur.siri21.util;
 
-import com.sun.xml.bind.marshaller.NamespacePrefixMapper;
 import org.entur.siri.XmlInputFactoryProvider;
-import uk.org.siri.siri21.Siri;
+import org.entur.siri.schema.v21.siri.Siri;
 
 import jakarta.xml.bind.JAXBContext;
 import jakarta.xml.bind.JAXBException;
@@ -31,6 +30,7 @@
 import java.io.OutputStream;
 import java.io.StringReader;
 import java.io.StringWriter;
+import java.util.function.Consumer;
 
 public class SiriXml {
 
@@ -71,12 +71,12 @@ public static String toXml(Siri siri) throws JAXBException {
         return toXml(siri, null);
     }
 
-    public static String toXml(Siri siri, NamespacePrefixMapper customNamespacePrefixMapper) throws JAXBException {
+    public static String toXml(Siri siri, Consumer<Marshaller> marshallerCustomizer) throws JAXBException {
 
         Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
 
-        if (customNamespacePrefixMapper != null) {
-            jaxbMarshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", customNamespacePrefixMapper);
+        if (marshallerCustomizer != null) {
+            marshallerCustomizer.accept(jaxbMarshaller);
         }
         StringWriter sw = new StringWriter();
         jaxbMarshaller.marshal(siri, sw);
@@ -84,11 +84,11 @@ public static String toXml(Siri siri, NamespacePrefixMapper customNamespacePrefi
         return sw.toString();
     }
 
-    public static void toXml(Siri siri, NamespacePrefixMapper customNamespacePrefixMapper, OutputStream out) throws JAXBException, IOException {
+    public static void toXml(Siri siri, Consumer<Marshaller> marshallerCustomizer, OutputStream out) throws JAXBException, IOException {
         Marshaller jaxbMarshaller = jaxbContext.createMarshaller();
 
-        if (customNamespacePrefixMapper != null) {
-            jaxbMarshaller.setProperty("com.sun.xml.bind.namespacePrefixMapper", customNamespacePrefixMapper);
+        if (marshallerCustomizer != null) {
+            marshallerCustomizer.accept(jaxbMarshaller);
         }
         jaxbMarshaller.marshal(siri, out);
     }
diff --git a/src/main/resources/siri-2.0/xjb/jaxb-bindings.xml b/src/main/resources/siri-2.0/xjb/jaxb-bindings.xml
index 4c9fa1f..c69c758 100644
--- a/src/main/resources/siri-2.0/xjb/jaxb-bindings.xml
+++ b/src/main/resources/siri-2.0/xjb/jaxb-bindings.xml
@@ -20,12 +20,8 @@
 
     <jaxb:globalBindings  >
 
-        <jaxb:javaType name="java.time.ZonedDateTime" xmlType="xsd:dateTime"
-                       printMethod="java.time.format.DateTimeFormatter.ISO_OFFSET_DATE_TIME.format"
-                       parseMethod="org.entur.siri.adapter.ZonedDateTimeAdapter.parse"/>
-        <jaxb:javaType name="java.time.ZonedDateTime" xmlType="xsd:time"
-                       printMethod="java.time.format.DateTimeFormatter.ISO_OFFSET_TIME.format"
-                       parseMethod="org.entur.siri.adapter.ZonedDateTimeAdapter.parse"/>
+        <xjc:javaType name="java.time.ZonedDateTime" xmlType="xsd:dateTime" adapter="org.entur.siri.adapter.ZonedDateTimeXmlAdapter" />
+        <xjc:javaType name="java.time.ZonedDateTime" xmlType="xsd:time" adapter="org.entur.siri.adapter.ZonedTimeXmlAdapter" />
         <xjc:javaType name="java.time.Duration" xmlType="xsd:duration" adapter="org.entur.siri.adapter.DurationXmlAdapter" />
         <xjc:simple/>
         <jaxb:serializable/>
@@ -33,25 +29,25 @@
 
     <jaxb:bindings schemaLocation="../xsd/siri.xsd">
         <jaxb:schemaBindings >
-            <jaxb:package name="uk.org.siri.siri20" />
+            <jaxb:package name="org.entur.siri.schema.v20.siri" />
         </jaxb:schemaBindings>
     </jaxb:bindings>
 
     <jaxb:bindings schemaLocation="../xsd/ifopt/ifopt_administration-v0.3.xsd">
         <jaxb:schemaBindings >
-            <jaxb:package name="uk.org.ifopt.siri20" />
+            <jaxb:package name="org.entur.siri.schema.v20.ifopt" />
         </jaxb:schemaBindings>
     </jaxb:bindings>
 
     <jaxb:bindings schemaLocation="../xsd/acsb/acsb_all-v0.3.xsd">
         <jaxb:schemaBindings >
-            <jaxb:package name="uk.org.acbs.siri20" />
+            <jaxb:package name="org.entur.siri.schema.v20.acsb" />
         </jaxb:schemaBindings>
     </jaxb:bindings>
 
     <jaxb:bindings schemaLocation="../xsd/datex2/DATEXIISchema_2_0RC1_2_0.xsd">
         <jaxb:schemaBindings >
-            <jaxb:package name="eu.datex2.siri20.schema._2_0rc1._2_0" />
+            <jaxb:package name="org.entur.siri.schema.v20.datex2" />
         </jaxb:schemaBindings>
     </jaxb:bindings>
 
diff --git a/src/main/resources/siri-2.1/xjb/jaxb-bindings.xml b/src/main/resources/siri-2.1/xjb/jaxb-bindings.xml
index c375d52..b549ec9 100644
--- a/src/main/resources/siri-2.1/xjb/jaxb-bindings.xml
+++ b/src/main/resources/siri-2.1/xjb/jaxb-bindings.xml
@@ -20,12 +20,8 @@
 
     <jaxb:globalBindings  >
 
-        <jaxb:javaType name="java.time.ZonedDateTime" xmlType="xsd:dateTime"
-                       printMethod="java.time.format.DateTimeFormatter.ISO_OFFSET_DATE_TIME.format"
-                       parseMethod="org.entur.siri.adapter.ZonedDateTimeAdapter.parse"/>
-        <jaxb:javaType name="java.time.ZonedDateTime" xmlType="xsd:time"
-                       printMethod="java.time.format.DateTimeFormatter.ISO_OFFSET_TIME.format"
-                       parseMethod="org.entur.siri.adapter.ZonedDateTimeAdapter.parse"/>
+        <xjc:javaType name="java.time.ZonedDateTime" xmlType="xsd:dateTime" adapter="org.entur.siri.adapter.ZonedDateTimeXmlAdapter" />
+        <xjc:javaType name="java.time.ZonedDateTime" xmlType="xsd:time" adapter="org.entur.siri.adapter.ZonedTimeXmlAdapter" />
         <xjc:javaType name="java.time.Duration" xmlType="xsd:duration" adapter="org.entur.siri.adapter.DurationXmlAdapter" />
         <xjc:simple/>
         <jaxb:serializable/>
@@ -33,30 +29,30 @@
 
     <jaxb:bindings schemaLocation="../xsd/siri.xsd">
         <jaxb:schemaBindings >
-            <jaxb:package name="uk.org.siri.siri21" />
+            <jaxb:package name="org.entur.siri.schema.v21.siri" />
         </jaxb:schemaBindings>
     </jaxb:bindings>
 
     <jaxb:bindings schemaLocation="../xsd/ifopt/ifopt_administration.xsd">
         <jaxb:schemaBindings >
-            <jaxb:package name="uk.org.ifopt.siri21" />
+            <jaxb:package name="org.entur.siri.schema.v21.ifopt" />
         </jaxb:schemaBindings>
     </jaxb:bindings>
 
     <jaxb:bindings schemaLocation="../xsd/acsb/acsb_all.xsd">
         <jaxb:schemaBindings >
-            <jaxb:package name="uk.org.acbs.siri21" />
+            <jaxb:package name="org.entur.siri.schema.v21.acsb" />
         </jaxb:schemaBindings>
     </jaxb:bindings>
 
     <jaxb:bindings schemaLocation="../xsd/datex2/DATEXIISchema.xsd">
         <jaxb:schemaBindings >
-            <jaxb:package name="eu.datex2.siri21.schema._2_0rc1._2_0" />
+            <jaxb:package name="org.entur.siri.schema.v21.datex2" />
         </jaxb:schemaBindings>
     </jaxb:bindings>
     <jaxb:bindings schemaLocation="../xsd/gml/gml_extract_all_objects.xsd">
         <jaxb:schemaBindings >
-            <jaxb:package name="net.opengis.gml.siri" />
+            <jaxb:package name="org.entur.siri.schema.v21.gml" />
         </jaxb:schemaBindings>
      </jaxb:bindings>
 
diff --git a/src/test/java/org/entur/siri/XmlInputFactoryProviderTest.java b/src/test/java/org/entur/siri/XmlInputFactoryProviderTest.java
index 08d7ed0..f632ff9 100644
--- a/src/test/java/org/entur/siri/XmlInputFactoryProviderTest.java
+++ b/src/test/java/org/entur/siri/XmlInputFactoryProviderTest.java
@@ -42,7 +42,7 @@ public class XmlInputFactoryProviderTest {
 
     @Test(expected = Exception.class)
     public void testXxeBlockedSiri20() throws Exception {
-        org.rutebanken.siri20.util.SiriXml.parseXml(XXE_XML);
+        org.entur.siri20.util.SiriXml.parseXml(XXE_XML);
     }
 
     @Test(expected = Exception.class)
diff --git a/src/test/java/org/entur/siri20/util/SiriXmlMarshallerCustomizerTest.java b/src/test/java/org/entur/siri20/util/SiriXmlMarshallerCustomizerTest.java
new file mode 100644
index 0000000..f916095
--- /dev/null
+++ b/src/test/java/org/entur/siri20/util/SiriXmlMarshallerCustomizerTest.java
@@ -0,0 +1,92 @@
+/*
+ * Licensed under the EUPL, Version 1.2 or – as soon they will be approved by
+ * the European Commission - subsequent versions of the EUPL (the "Licence");
+ * You may not use this work except in compliance with the Licence.
+ * You may obtain a copy of the Licence at:
+ *
+ *   https://joinup.ec.europa.eu/software/page/eupl
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the Licence is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the Licence for the specific language governing permissions and
+ * limitations under the Licence.
+ */
+
+package org.entur.siri20.util;
+
+import jakarta.xml.bind.Marshaller;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.entur.siri.schema.v20.siri.Siri;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.entur.siri20.util.SiriXml.parseXml;
+import static org.entur.siri20.util.SiriXml.toXml;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class SiriXmlMarshallerCustomizerTest {
+
+    private static Siri siri;
+
+    @BeforeClass
+    public static void init() throws Exception {
+        String xml = new String(Files.readAllBytes(Paths.get("src/test/resources/et.xml")), StandardCharsets.UTF_8);
+        siri = parseXml(xml);
+    }
+
+    @Test
+    public void testCustomizerIsAppliedToMarshaller() throws Exception {
+        AtomicInteger calls = new AtomicInteger();
+
+        String formatted = toXml(siri, marshaller -> {
+            calls.incrementAndGet();
+            setFormattedOutput(marshaller);
+        });
+
+        assertEquals(1, calls.get());
+        assertTrue("Expected indented output", isIndented(formatted));
+    }
+
+    @Test
+    public void testNullCustomizerGivesSameOutputAsDefault() throws Exception {
+        assertEquals(toXml(siri), toXml(siri, null));
+    }
+
+    @Test
+    public void testCustomizerIsAppliedWhenWritingToOutputStream() throws Exception {
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+
+        SiriXml.toXml(siri, SiriXmlMarshallerCustomizerTest::setFormattedOutput, out);
+
+        String formatted = new String(out.toByteArray(), StandardCharsets.UTF_8);
+        assertTrue("Expected indented output", isIndented(formatted));
+    }
+
+    @Test
+    public void testCustomizerDoesNotLeakIntoLaterCalls() throws Exception {
+        toXml(siri, SiriXmlMarshallerCustomizerTest::setFormattedOutput);
+
+        assertFalse("Customizer must only affect its own marshaller", isIndented(toXml(siri)));
+    }
+
+    private static boolean isIndented(String xml) {
+        return xml.split("\n").length > 5;
+    }
+
+    private static void setFormattedOutput(Marshaller marshaller) {
+        try {
+            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
+        } catch (Exception e) {
+            throw new IllegalStateException(e);
+        }
+    }
+}
diff --git a/src/test/java/org/entur/siri21/util/MarshallingTest.java b/src/test/java/org/entur/siri21/util/MarshallingTest.java
index 107c4ce..00eb8f1 100644
--- a/src/test/java/org/entur/siri21/util/MarshallingTest.java
+++ b/src/test/java/org/entur/siri21/util/MarshallingTest.java
@@ -17,7 +17,7 @@
 
 import org.junit.BeforeClass;
 import org.junit.Test;
-import uk.org.siri.siri21.Siri;
+import org.entur.siri.schema.v21.siri.Siri;
 
 import java.io.IOException;
 import java.io.RandomAccessFile;
diff --git a/src/test/java/org/entur/siri21/util/SiriJsonTest.java b/src/test/java/org/entur/siri21/util/SiriJsonTest.java
index 3722a15..316d138 100644
--- a/src/test/java/org/entur/siri21/util/SiriJsonTest.java
+++ b/src/test/java/org/entur/siri21/util/SiriJsonTest.java
@@ -17,7 +17,7 @@
 
 import org.junit.BeforeClass;
 import org.junit.Test;
-import uk.org.siri.siri21.Siri;
+import org.entur.siri.schema.v21.siri.Siri;
 
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
diff --git a/src/test/java/org/entur/siri21/util/SiriXmlMarshallerCustomizerTest.java b/src/test/java/org/entur/siri21/util/SiriXmlMarshallerCustomizerTest.java
new file mode 100644
index 0000000..73abcfe
--- /dev/null
+++ b/src/test/java/org/entur/siri21/util/SiriXmlMarshallerCustomizerTest.java
@@ -0,0 +1,114 @@
+    /*
+ * Licensed under the EUPL, Version 1.2 or – as soon they will be approved by
+ * the European Commission - subsequent versions of the EUPL (the "Licence");
+ * You may not use this work except in compliance with the Licence.
+ * You may obtain a copy of the Licence at:
+ *
+ *   https://joinup.ec.europa.eu/software/page/eupl
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the Licence is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the Licence for the specific language governing permissions and
+ * limitations under the Licence.
+ */
+
+package org.entur.siri21.util;
+
+import jakarta.xml.bind.Marshaller;
+import org.glassfish.jaxb.runtime.marshaller.NamespacePrefixMapper;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import org.entur.siri.schema.v21.siri.Siri;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Paths;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import static org.entur.siri21.util.SiriXml.parseXml;
+import static org.entur.siri21.util.SiriXml.toXml;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class SiriXmlMarshallerCustomizerTest {
+
+    private static Siri siri;
+
+    @BeforeClass
+    public static void init() throws Exception {
+        String xml = new String(Files.readAllBytes(Paths.get("src/test/resources/et-2_1.xml")), StandardCharsets.UTF_8);
+        siri = parseXml(xml);
+    }
+
+    @Test
+    public void testCustomizerIsAppliedToMarshaller() throws Exception {
+        AtomicInteger calls = new AtomicInteger();
+
+        String formatted = toXml(siri, marshaller -> {
+            calls.incrementAndGet();
+            setFormattedOutput(marshaller);
+        });
+
+        assertEquals(1, calls.get());
+        assertTrue("Expected indented output", isIndented(formatted));
+    }
+
+    @Test
+    public void testJaxbRiNamespacePrefixMapperCanBeSetThroughCustomizer() throws Exception {
+        NamespacePrefixMapper mapper = new NamespacePrefixMapper() {
+            @Override
+            public String getPreferredPrefix(String namespaceUri, String suggestion, boolean requirePrefix) {
+                return "http://www.siri.org.uk/siri".equals(namespaceUri) ? "siri" : suggestion;
+            }
+        };
+
+        String xml = toXml(siri, marshaller -> {
+            try {
+                marshaller.setProperty("org.glassfish.jaxb.namespacePrefixMapper", mapper);
+            } catch (Exception e) {
+                throw new IllegalStateException(e);
+            }
+        });
+
+        assertTrue("Expected siri: prefix", xml.contains("<siri:Siri"));
+        assertFalse("Default output should not use a prefix", toXml(siri).contains("<siri:Siri"));
+    }
+
+    @Test
+    public void testNullCustomizerGivesSameOutputAsDefault() throws Exception {
+        assertEquals(toXml(siri), toXml(siri, null));
+    }
+
+    @Test
+    public void testCustomizerIsAppliedWhenWritingToOutputStream() throws Exception {
+        ByteArrayOutputStream out = new ByteArrayOutputStream();
+
+        SiriXml.toXml(siri, SiriXmlMarshallerCustomizerTest::setFormattedOutput, out);
+
+        String formatted = new String(out.toByteArray(), StandardCharsets.UTF_8);
+        assertTrue("Expected indented output", isIndented(formatted));
+    }
+
+    @Test
+    public void testCustomizerDoesNotLeakIntoLaterCalls() throws Exception {
+        toXml(siri, SiriXmlMarshallerCustomizerTest::setFormattedOutput);
+
+        assertFalse("Customizer must only affect its own marshaller", isIndented(toXml(siri)));
+    }
+
+    private static boolean isIndented(String xml) {
+        return xml.split("\n").length > 5;
+    }
+
+    private static void setFormattedOutput(Marshaller marshaller) {
+        try {
+            marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
+        } catch (Exception e) {
+            throw new IllegalStateException(e);
+        }
+    }
+}
diff --git a/src/test/java/org/entur/siri21/util/SiriXmlTest.java b/src/test/java/org/entur/siri21/util/SiriXmlTest.java
index ec215d0..46c28b8 100644
--- a/src/test/java/org/entur/siri21/util/SiriXmlTest.java
+++ b/src/test/java/org/entur/siri21/util/SiriXmlTest.java
@@ -18,7 +18,7 @@
 import org.entur.siri.validator.SiriValidator;
 import org.junit.BeforeClass;
 import org.junit.Test;
-import uk.org.siri.siri21.Siri;
+import org.entur.siri.schema.v21.siri.Siri;
 
 import java.io.IOException;
 import java.io.RandomAccessFile;