diff --git a/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/term/BaseHapiTerminologySvcImpl.java b/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/term/BaseHapiTerminologySvcImpl.java
index f1a8d5b49f3..daef9c67328 100644
--- a/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/term/BaseHapiTerminologySvcImpl.java
+++ b/hapi-fhir-jpaserver-base/src/main/java/ca/uhn/fhir/jpa/term/BaseHapiTerminologySvcImpl.java
@@ -990,22 +990,33 @@ public abstract class BaseHapiTerminologySvcImpl implements IHapiTerminologySvc,
 	}
 
 	private void addLoincFilterAncestorEqual(String theSystem, QueryBuilder theQb, BooleanJunction<?> theBool, ValueSet.ConceptSetFilterComponent theFilter) {
-		TermConcept code = findCode(theSystem, theFilter.getValue())
-			.orElseThrow(() -> new InvalidRequestException("Invalid filter criteria - code does not exist: {" + theSystem + "}" + theFilter.getValue()));
+		addLoincFilterAncestorEqual(theSystem, theQb, theBool, theFilter.getProperty(), theFilter.getValue());
+	}
 
-		logFilteringValueOnProperty(theFilter.getValue(), theFilter.getProperty());
-		theBool.must(theQb.keyword().onField("myParentPids").matching("" + code.getId()).createQuery());
+	private void addLoincFilterAncestorEqual(String theSystem, QueryBuilder theQb, BooleanJunction<?> theBool, String theProperty, String theValue) {
+		List<Term> terms = getAncestorTerms(theSystem, theProperty, theValue);
+		theBool.must(new TermsQuery(terms));
 	}
 
 	private void addLoincFilterAncestorIn(String theSystem, QueryBuilder theQb, BooleanJunction<?> theBool, ValueSet.ConceptSetFilterComponent theFilter) {
-		throw new UnsupportedOperationException();
-		// FIXME: DM 2019-09-30 - Working on this presently.
-		// FIXME: DM 2019-09-25 - Filter with op=IN on ancestor; see #1512 in GitHub.
-		// FIXME: DM 2019-09-26 - Once implemented, fix changelog entry for #1454 in changes.xml
-//		String[] values = theFilter.getValue().split(",");
-//		for (String value : values) {
-//			logFilteringValueOnProperty(value, theFilter.getProperty());
-//		}
+		String[] values = theFilter.getValue().split(",");
+		List<Term> terms = new ArrayList<>();
+		for (String value : values) {
+			terms.addAll(getAncestorTerms(theSystem, theFilter.getProperty(), value));
+		}
+		theBool.must(new TermsQuery(terms));
+	}
+
+	private List<Term> getAncestorTerms(String theSystem, String theProperty, String theValue) {
+		List<Term> retVal = new ArrayList<>();
+
+		TermConcept code = findCode(theSystem, theValue)
+			.orElseThrow(() -> new InvalidRequestException("Invalid filter criteria - code does not exist: {" + theSystem + "}" + theValue));
+
+		retVal.add(new Term("myParentPids", "" + code.getId()));
+		logFilteringValueOnProperty(theValue, theProperty);
+
+		return retVal;
 	}
 
 	private void handleFilterLoincDescendant(String theSystem, QueryBuilder theQb, BooleanJunction<?> theBool, ValueSet.ConceptSetFilterComponent theFilter) {
diff --git a/hapi-fhir-jpaserver-base/src/test/java/ca/uhn/fhir/jpa/term/TerminologySvcImplDstu3Test.java b/hapi-fhir-jpaserver-base/src/test/java/ca/uhn/fhir/jpa/term/TerminologySvcImplDstu3Test.java
index e2153aa4e63..9d2d785b5ee 100644
--- a/hapi-fhir-jpaserver-base/src/test/java/ca/uhn/fhir/jpa/term/TerminologySvcImplDstu3Test.java
+++ b/hapi-fhir-jpaserver-base/src/test/java/ca/uhn/fhir/jpa/term/TerminologySvcImplDstu3Test.java
@@ -619,7 +619,6 @@ public class TerminologySvcImplDstu3Test extends BaseJpaDstu3Test {
 		assertThat(codes, containsInAnyOrder("50015-7", "43343-3", "43343-4", "47239-9"));
 	}
 
-	@Ignore("Not yet implemented; see #1512 in GitHub.")
 	@Test
 	public void testExpandValueSetPropertyFilterLoincAncestorWithExcludeAndIn() {
 		createLoincSystemWithSomeCodes();
@@ -707,7 +706,6 @@ public class TerminologySvcImplDstu3Test extends BaseJpaDstu3Test {
 		assertEquals(0, outcome.getExpansion().getContains().size());
 	}
 
-	@Ignore("Not yet implemented; see #1512 in GitHub.")
 	@Test
 	public void testExpandValueSetPropertyFilterLoincAncestorWithIncludeAndIn() {
 		createLoincSystemWithSomeCodes();
diff --git a/src/changes/changes.xml b/src/changes/changes.xml
index 816f7f06dea..b72f400977b 100644
--- a/src/changes/changes.xml
+++ b/src/changes/changes.xml
@@ -249,6 +249,10 @@
 				<![CDATA[<code>=</code>]]> or <![CDATA[<code>in</code>]]> operators. At present, the
 				<![CDATA[<code>ancestor</code>]]> filter can only be used with the <![CDATA[<code>=</code>]]> operator.
 			</action>
+			<action type="add" issue="1512">
+				Support for the LOINC <![CDATA[<code>ancestor</code>]]> filter with the <![CDATA[<code>in</code>]]>
+				operator has been added.
+			</action>
 			<action type="fix">
 				The JPA server failed to find codes defined in not-present codesystems in some cases, and reported
 				that the CodeSystem did not exist. This has been corrected.