diff --git a/hibernate-core/src/test/java/org/hibernate/orm/test/mapping/collections/MapKeyToOneInEmbeddedIdTest.java b/hibernate-core/src/test/java/org/hibernate/orm/test/mapping/collections/MapKeyToOneInEmbeddedIdTest.java
new file mode 100644
index 0000000000..44c3c27ecd
--- /dev/null
+++ b/hibernate-core/src/test/java/org/hibernate/orm/test/mapping/collections/MapKeyToOneInEmbeddedIdTest.java
@@ -0,0 +1,166 @@
+/*
+ * Hibernate, Relational Persistence for Idiomatic Java
+ *
+ * License: GNU Lesser General Public License (LGPL), version 2.1 or later
+ * See the lgpl.txt file in the root directory or http://www.gnu.org/licenses/lgpl-2.1.html
+ */
+package org.hibernate.orm.test.mapping.collections;
+
+import java.io.Serializable;
+import java.util.HashMap;
+import java.util.Map;
+
+import org.hibernate.testing.orm.junit.DomainModel;
+import org.hibernate.testing.orm.junit.Jira;
+import org.hibernate.testing.orm.junit.SessionFactory;
+import org.hibernate.testing.orm.junit.SessionFactoryScope;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+import jakarta.persistence.Embeddable;
+import jakarta.persistence.EmbeddedId;
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+import jakarta.persistence.ManyToMany;
+import jakarta.persistence.ManyToOne;
+import jakarta.persistence.MapKey;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Marco Belladelli
+ */
+@DomainModel( annotatedClasses = {
+		MapKeyToOneInEmbeddedIdTest.EntityA.class,
+		MapKeyToOneInEmbeddedIdTest.EntityBID.class,
+		MapKeyToOneInEmbeddedIdTest.EntityB.class,
+		MapKeyToOneInEmbeddedIdTest.EntityC.class,
+} )
+@SessionFactory
+@Jira( "https://hibernate.atlassian.net/browse/HHH-17285" )
+public class MapKeyToOneInEmbeddedIdTest {
+	@BeforeAll
+	public void setUp(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final EntityC entityC = new EntityC( "entity_c" );
+			session.persist( entityC );
+			final EntityB entityB = new EntityB( new EntityBID( entityC, 1 ), "entity_b" );
+			session.persist( entityB );
+			final EntityA entityA = new EntityA( 1 );
+			entityA.getbEntities().put( entityC, entityB );
+			session.persist( entityA );
+		} );
+	}
+
+	@AfterAll
+	public void tearDown(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			session.createMutationQuery( "delete from EntityA" ).executeUpdate();
+			session.createMutationQuery( "delete from EntityB" ).executeUpdate();
+			session.createMutationQuery( "delete from EntityC" ).executeUpdate();
+		} );
+	}
+
+	@Test
+	public void testMapping(SessionFactoryScope scope) {
+		scope.inTransaction( session -> {
+			final EntityA entityA = session.find( EntityA.class, 1 );
+			assertThat( entityA.getbEntities() ).hasSize( 1 );
+			final Map.Entry<EntityC, EntityB> entry = entityA.getbEntities().entrySet().iterator().next();
+			assertThat( entry.getKey().getName() ).isEqualTo( "entity_c" );
+			assertThat( entry.getValue().getName() ).isEqualTo( "entity_b" );
+			assertThat( entry.getValue().getId().getEntity() ).isSameAs( entry.getKey() );
+		} );
+	}
+
+	@Entity( name = "EntityA" )
+	public static class EntityA {
+		@Id
+		private Integer id;
+
+		@ManyToMany
+		@MapKey( name = "id.entity" )
+		private Map<EntityC, EntityB> bEntities = new HashMap<>();
+
+		public EntityA() {
+		}
+
+		public EntityA(Integer id) {
+			this.id = id;
+		}
+
+		public Map<EntityC, EntityB> getbEntities() {
+			return bEntities;
+		}
+	}
+
+	@Embeddable
+	public static class EntityBID implements Serializable {
+		@ManyToOne
+		private EntityC entity;
+
+		private Integer code;
+
+		public EntityBID() {
+		}
+
+		public EntityBID(EntityC entity, Integer code) {
+			this.entity = entity;
+			this.code = code;
+		}
+
+		public EntityC getEntity() {
+			return entity;
+		}
+
+		public Integer getCode() {
+			return code;
+		}
+	}
+
+	@Entity( name = "EntityB" )
+	public static class EntityB {
+		@EmbeddedId
+		private EntityBID id;
+
+		private String name;
+
+		public EntityB() {
+		}
+
+		public EntityB(EntityBID id, String name) {
+			this.id = id;
+			this.name = name;
+		}
+
+		public EntityBID getId() {
+			return id;
+		}
+
+		public String getName() {
+			return name;
+		}
+	}
+
+	@Entity( name = "EntityC" )
+	public static class EntityC {
+		@Id
+		@GeneratedValue
+		private Integer id;
+
+		private String name;
+
+		public EntityC() {
+		}
+
+		public EntityC(String name) {
+			this.name = name;
+		}
+
+		public String getName() {
+			return name;
+		}
+	}
+}