diff --git a/hibernate-core/src/main/java/org/hibernate/jpa/internal/PersistenceUnitUtilImpl.java b/hibernate-core/src/main/java/org/hibernate/jpa/internal/PersistenceUnitUtilImpl.java
index 378a783d1b..2caf603ebb 100644
--- a/hibernate-core/src/main/java/org/hibernate/jpa/internal/PersistenceUnitUtilImpl.java
+++ b/hibernate-core/src/main/java/org/hibernate/jpa/internal/PersistenceUnitUtilImpl.java
@@ -11,6 +11,7 @@ import javax.persistence.PersistenceUnitUtil;
 import javax.persistence.spi.LoadState;
 
 import org.hibernate.Hibernate;
+import org.hibernate.engine.spi.EntityEntry;
 import org.hibernate.engine.spi.ManagedEntity;
 import org.hibernate.engine.spi.SessionFactoryImplementor;
 import org.hibernate.jpa.internal.util.PersistenceUtilHelper;
@@ -66,12 +67,18 @@ public class PersistenceUnitUtilImpl implements PersistenceUnitUtil, Serializabl
 		}
 
 		if ( entity instanceof HibernateProxy ) {
-			final HibernateProxy proxy = (HibernateProxy) entity;
-			return proxy.getHibernateLazyInitializer().getIdentifier();
+			return ((HibernateProxy) entity).getHibernateLazyInitializer().getIdentifier();
 		}
 		else if ( entity instanceof ManagedEntity ) {
-			final ManagedEntity enhancedEntity = (ManagedEntity) entity;
-			return enhancedEntity.$$_hibernate_getEntityEntry().getId();
+			EntityEntry entityEntry = ((ManagedEntity) entity).$$_hibernate_getEntityEntry();
+			if ( entityEntry != null ) {
+				return entityEntry.getId();
+			}
+			else {
+				// HHH-11426 - best effort to deal with the case of detached entities
+				log.debug( "javax.persistence.PersistenceUnitUtil.getIdentifier may not be able to read identifier of a detached entity" );
+				return getIdentifierFromPersister( entity );
+			}
 		}
 		else {
 			log.debugf(
@@ -79,13 +86,17 @@ public class PersistenceUnitUtilImpl implements PersistenceUnitUtil, Serializabl
 							"(although Hibernate also adapts this support to its proxies); " +
 							"however the passed entity was not enhanced (nor a proxy).. may not be able to read identifier"
 			);
-			final Class entityClass = Hibernate.getClass( entity );
-			final EntityPersister persister = sessionFactory.getMetamodel().entityPersister( entityClass );
-			if ( persister == null ) {
-				throw new IllegalArgumentException( entityClass + " is not an entity" );
-			}
-			//TODO does that work for @IdClass?
-			return persister.getIdentifier( entity );
+			return getIdentifierFromPersister( entity );
 		}
 	}
+
+	private Object getIdentifierFromPersister(Object entity) {
+		Class<?> entityClass = Hibernate.getClass( entity );
+		EntityPersister persister = sessionFactory.getMetamodel().entityPersister( entityClass );
+		if ( persister == null ) {
+			throw new IllegalArgumentException( entityClass.getName() + " is not an entity" );
+		}
+		return persister.getIdentifier( entity, null );
+	}
+
 }
diff --git a/hibernate-core/src/test/java/org/hibernate/test/bytecode/enhancement/EnhancerTest.java b/hibernate-core/src/test/java/org/hibernate/test/bytecode/enhancement/EnhancerTest.java
index be598228c9..42b2a110de 100644
--- a/hibernate-core/src/test/java/org/hibernate/test/bytecode/enhancement/EnhancerTest.java
+++ b/hibernate-core/src/test/java/org/hibernate/test/bytecode/enhancement/EnhancerTest.java
@@ -8,6 +8,7 @@ package org.hibernate.test.bytecode.enhancement;
 
 import org.hibernate.bytecode.enhance.spi.UnloadedClass;
 
+import org.hibernate.test.bytecode.enhancement.detached.DetachedGetIdentifierTestTask;
 import org.hibernate.testing.FailureExpected;
 import org.hibernate.testing.TestForIssue;
 import org.hibernate.testing.bytecode.enhancement.EnhancerTestContext;
@@ -83,6 +84,12 @@ public class EnhancerTest extends BaseUnitTestCase {
 		EnhancerTestUtils.runEnhancerTestTask( DirtyTrackingTestTask.class );
 	}
 
+	@Test
+	@TestForIssue( jiraKey = "HHH-11426" )
+	public void testDetached() {
+		EnhancerTestUtils.runEnhancerTestTask( DetachedGetIdentifierTestTask.class );
+	}
+
 	@Test
 	public void testEviction() {
 		EnhancerTestUtils.runEnhancerTestTask( EvictionTestTask.class );
diff --git a/hibernate-core/src/test/java/org/hibernate/test/bytecode/enhancement/detached/DetachedGetIdentifierTestTask.java b/hibernate-core/src/test/java/org/hibernate/test/bytecode/enhancement/detached/DetachedGetIdentifierTestTask.java
new file mode 100644
index 0000000000..76a263900e
--- /dev/null
+++ b/hibernate-core/src/test/java/org/hibernate/test/bytecode/enhancement/detached/DetachedGetIdentifierTestTask.java
@@ -0,0 +1,59 @@
+package org.hibernate.test.bytecode.enhancement.detached;
+
+import org.hibernate.cfg.Configuration;
+import org.hibernate.cfg.Environment;
+import org.hibernate.test.bytecode.enhancement.AbstractEnhancerTestTask;
+import org.junit.Assert;
+
+import javax.persistence.Entity;
+import javax.persistence.EntityManager;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+
+/**
+ * @author Luis Barreiro
+ */
+public class DetachedGetIdentifierTestTask extends AbstractEnhancerTestTask {
+
+    public Class<?>[] getAnnotatedClasses() {
+        return new Class<?>[]{SimpleEntity.class};
+    }
+
+    public void prepare() {
+        Configuration cfg = new Configuration();
+        cfg.setProperty( Environment.ENABLE_LAZY_LOAD_NO_TRANS, "true" );
+        cfg.setProperty( Environment.USE_SECOND_LEVEL_CACHE, "false" );
+        super.prepare( cfg );
+    }
+
+    public void execute() {
+        EntityManager em = getFactory().createEntityManager();
+        em.getTransaction().begin();
+
+        SimpleEntity se = new SimpleEntity();
+        se.name = "test";
+        se = em.merge( se );
+
+        Assert.assertNotNull( getFactory().getPersistenceUnitUtil().getIdentifier( se ) );
+
+        em.getTransaction().commit();
+        em.close();
+
+        // Call as detached entity
+        Assert.assertNotNull( getFactory().getPersistenceUnitUtil().getIdentifier( se ) );
+    }
+
+    protected void cleanup() {
+    }
+
+    @Entity
+    public static class SimpleEntity {
+
+        @Id
+        @GeneratedValue
+        private Long id;
+
+        private String name;
+
+    }
+}