diff --git a/java/google/registry/flows/host/HostUpdateFlow.java b/java/google/registry/flows/host/HostUpdateFlow.java
index 857bd09f5..df838c956 100644
--- a/java/google/registry/flows/host/HostUpdateFlow.java
+++ b/java/google/registry/flows/host/HostUpdateFlow.java
@@ -155,7 +155,7 @@ public final class HostUpdateFlow implements TransactionalFlow {
         // the lookupSuperordinateDomain(...) call above, so that it will never be stale.
         .setSuperordinateDomain(
             superordinateDomain.isPresent() ? Key.create(superordinateDomain.get()) : null)
-        .setLastSuperordinateChange(superordinateDomain == null ? null : now)
+        .setLastSuperordinateChange(superordinateDomain.isPresent() ? now : null)
         .build()
         // Rely on the host's cloneProjectedAtTime() method to handle setting of transfer data.
         .cloneProjectedAtTime(now);
diff --git a/javatests/google/registry/flows/host/HostUpdateFlowTest.java b/javatests/google/registry/flows/host/HostUpdateFlowTest.java
index 0e6c412db..0264328ca 100644
--- a/javatests/google/registry/flows/host/HostUpdateFlowTest.java
+++ b/javatests/google/registry/flows/host/HostUpdateFlowTest.java
@@ -562,6 +562,8 @@ public class HostUpdateFlowTest extends ResourceFlowTestCase<HostUpdateFlow, Hos
     // The last transfer time should be what was on the superordinate domain at the time of the host
     // update, not what it is later changed to.
     assertThat(renamedHost.getLastTransferTime()).isEqualTo(lastTransferTime);
+    // External hosts should always have null lastSuperordinateChange.
+    assertThat(renamedHost.getLastSuperordinateChange()).isNull();
   }
 
   @Test