diff --git a/java/google/registry/tools/RegistrarContactCommand.java b/java/google/registry/tools/RegistrarContactCommand.java
index a0eb2d972..7e3e78637 100644
--- a/java/google/registry/tools/RegistrarContactCommand.java
+++ b/java/google/registry/tools/RegistrarContactCommand.java
@@ -18,7 +18,6 @@ import static com.google.common.base.Preconditions.checkArgument;
 import static com.google.common.base.Preconditions.checkNotNull;
 import static com.google.common.base.Strings.isNullOrEmpty;
 import static com.google.common.collect.Iterables.transform;
-import static com.google.common.collect.Sets.newHashSet;
 import static google.registry.util.CollectionUtils.nullToEmpty;
 import static google.registry.util.PreconditionsUtils.checkArgumentNotNull;
 import static java.nio.charset.StandardCharsets.UTF_8;
@@ -144,7 +143,7 @@ final class RegistrarContactCommand extends MutatingCommand {
       ImmutableSet.of(Mode.CREATE, Mode.UPDATE, Mode.DELETE);
 
   @Nullable
-  private Set<RegistrarContact.Type> contactTypes;
+  private ImmutableSet<RegistrarContact.Type> contactTypes;
 
   @Override
   protected void init() throws Exception {
@@ -153,10 +152,21 @@ final class RegistrarContactCommand extends MutatingCommand {
     String clientId = mainParameters.get(0);
     Registrar registrar =
         checkNotNull(Registrar.loadByClientId(clientId), "Registrar %s not found", clientId);
-    contactTypes =
-        newHashSet(
-            transform(
-                nullToEmpty(contactTypeNames), Enums.stringConverter(RegistrarContact.Type.class)));
+    // If the contact_type parameter is not specified, we should not make any changes.
+    if (contactTypeNames == null) {
+      contactTypes = null;
+    // It appears that when the user specifies "--contact_type=" with no types following, JCommander
+    // sets contactTypeNames to a one-element list containing the empty string. This is strange, but
+    // we need to handle this by setting the contact types to the empty set. Also do this if
+    // contactTypeNames is empty, which is what I would hope JCommander would return in some future,
+    // better world.
+    } else if (contactTypeNames.isEmpty()
+        || ((contactTypeNames.size() == 1) && contactTypeNames.get(0).isEmpty())) {
+      contactTypes = ImmutableSet.of();
+    } else {
+      contactTypes = ImmutableSet.copyOf(
+              transform(contactTypeNames, Enums.stringConverter(RegistrarContact.Type.class)));
+    }
     ImmutableSet<RegistrarContact> contacts = registrar.getContacts();
     Map<String, RegistrarContact> contactsMap = new LinkedHashMap<>();
     for (RegistrarContact rc : contacts) {
@@ -169,7 +179,9 @@ final class RegistrarContactCommand extends MutatingCommand {
         break;
       case CREATE:
         stageEntityChange(null, createContact(registrar));
-        unsetOtherWhoisAbuseFlags(contacts, null);
+        if ((visibleInDomainWhoisAsAbuse != null) && visibleInDomainWhoisAsAbuse.booleanValue()) {
+          unsetOtherWhoisAbuseFlags(contacts, null /* emailAddressNotToChange */ );
+        }
         break;
       case UPDATE:
         oldContact =
@@ -184,7 +196,9 @@ final class RegistrarContactCommand extends MutatingCommand {
             "Cannot clear visible_in_domain_whois_as_abuse flag, as that would leave no domain"
                 + " WHOIS abuse contacts; instead, set the flag on another contact");
         stageEntityChange(oldContact, newContact);
-        unsetOtherWhoisAbuseFlags(contacts, oldContact.getEmailAddress());
+        if ((visibleInDomainWhoisAsAbuse != null) && visibleInDomainWhoisAsAbuse.booleanValue()) {
+          unsetOtherWhoisAbuseFlags(contacts, oldContact.getEmailAddress());
+        }
         break;
       case DELETE:
         oldContact =
@@ -226,7 +240,7 @@ final class RegistrarContactCommand extends MutatingCommand {
     if (fax != null) {
       builder.setFaxNumber(fax.orNull());
     }
-    builder.setTypes(contactTypes);
+    builder.setTypes(nullToEmpty(contactTypes));
 
     if (Objects.equals(allowConsoleAccess, Boolean.TRUE)) {
       builder.setGaeUserId(checkArgumentNotNull(
diff --git a/javatests/google/registry/tools/RegistrarContactCommandTest.java b/javatests/google/registry/tools/RegistrarContactCommandTest.java
index 7a2f7d2c0..334ac7129 100644
--- a/javatests/google/registry/tools/RegistrarContactCommandTest.java
+++ b/javatests/google/registry/tools/RegistrarContactCommandTest.java
@@ -17,6 +17,7 @@ package google.registry.tools;
 import static com.google.common.truth.Truth.assertThat;
 import static google.registry.model.registrar.RegistrarContact.Type.ABUSE;
 import static google.registry.model.registrar.RegistrarContact.Type.ADMIN;
+import static google.registry.model.registrar.RegistrarContact.Type.TECH;
 import static google.registry.model.registrar.RegistrarContact.Type.WHOIS;
 import static google.registry.testing.DatastoreHelper.persistResource;
 import static google.registry.testing.DatastoreHelper.persistSimpleResource;
@@ -208,6 +209,85 @@ public class RegistrarContactCommandTest extends CommandTestCase<RegistrarContac
     assertThat(registrarContact.getVisibleInDomainWhoisAsAbuse()).isTrue();
   }
 
+  @Test
+  public void testUpdate_emptyCommandModifiesNothing() throws Exception {
+    Registrar registrar = Registrar.loadByClientId("NewRegistrar");
+    RegistrarContact existingContact = persistSimpleResource(
+        new RegistrarContact.Builder()
+            .setParent(registrar)
+            .setName("John Doe")
+            .setEmailAddress("john.doe@example.com")
+            .setGaeUserId("11111")
+            .setPhoneNumber("123-456-7890")
+            .setFaxNumber("123-456-7890")
+            .setTypes(ImmutableSet.of(ADMIN, ABUSE))
+            .setVisibleInWhoisAsAdmin(true)
+            .setVisibleInWhoisAsTech(true)
+            .setVisibleInDomainWhoisAsAbuse(true)
+            .build());
+    runCommandForced("--mode=UPDATE", "--email=john.doe@example.com", "NewRegistrar");
+    RegistrarContact registrarContact =
+        Registrar.loadByClientId("NewRegistrar").getContacts().asList().get(1);
+    assertThat(registrarContact.getEmailAddress()).isEqualTo(existingContact.getEmailAddress());
+    assertThat(registrarContact.getName()).isEqualTo(existingContact.getName());
+    assertThat(registrarContact.getGaeUserId()).isEqualTo(existingContact.getGaeUserId());
+    assertThat(registrarContact.getPhoneNumber()).isEqualTo(existingContact.getPhoneNumber());
+    assertThat(registrarContact.getFaxNumber()).isEqualTo(existingContact.getFaxNumber());
+    assertThat(registrarContact.getTypes()).isEqualTo(existingContact.getTypes());
+    assertThat(registrarContact.getVisibleInWhoisAsAdmin())
+        .isEqualTo(existingContact.getVisibleInWhoisAsAdmin());
+    assertThat(registrarContact.getVisibleInWhoisAsTech())
+        .isEqualTo(existingContact.getVisibleInWhoisAsTech());
+    assertThat(registrarContact.getVisibleInDomainWhoisAsAbuse())
+        .isEqualTo(existingContact.getVisibleInDomainWhoisAsAbuse());
+  }
+
+  @Test
+  public void testUpdate_listOfTypesWorks() throws Exception {
+    Registrar registrar = Registrar.loadByClientId("NewRegistrar");
+    persistSimpleResource(
+        new RegistrarContact.Builder()
+            .setParent(registrar)
+            .setName("John Doe")
+            .setEmailAddress("john.doe@example.com")
+            .setGaeUserId("11111")
+            .setPhoneNumber("123-456-7890")
+            .setFaxNumber("123-456-7890")
+            .setTypes(ImmutableSet.of(ADMIN, ABUSE))
+            .setVisibleInWhoisAsAdmin(true)
+            .setVisibleInWhoisAsTech(true)
+            .setVisibleInDomainWhoisAsAbuse(true)
+            .build());
+    runCommandForced(
+        "--mode=UPDATE",
+        "--email=john.doe@example.com",
+        "--contact_type=ADMIN,TECH",
+        "NewRegistrar");
+    RegistrarContact registrarContact =
+        Registrar.loadByClientId("NewRegistrar").getContacts().asList().get(1);
+    assertThat(registrarContact.getTypes()).containsExactly(ADMIN, TECH);
+  }
+
+  @Test
+  public void testUpdate_clearAllTypes() throws Exception {
+    Registrar registrar = Registrar.loadByClientId("NewRegistrar");
+    persistSimpleResource(
+        new RegistrarContact.Builder()
+            .setParent(registrar)
+            .setName("John Doe")
+            .setEmailAddress("john.doe@example.com")
+            .setTypes(ImmutableSet.of(ADMIN, ABUSE))
+            .build());
+    runCommandForced(
+        "--mode=UPDATE",
+        "--email=john.doe@example.com",
+        "--contact_type=",
+        "NewRegistrar");
+    RegistrarContact registrarContact =
+        Registrar.loadByClientId("NewRegistrar").getContacts().asList().get(1);
+    assertThat(registrarContact.getTypes()).isEmpty();
+  }
+
   @Test
   public void testCreate_withAdminType() throws Exception {
     Registrar registrar = Registrar.loadByClientId("NewRegistrar");
@@ -278,6 +358,18 @@ public class RegistrarContactCommandTest extends CommandTestCase<RegistrarContac
     assertThat(registrarContact.getGaeUserId()).matches("-?[0-9]+");
   }
 
+  @Test
+  public void testCreate_withNoContactTypes() throws Exception {
+    runCommandForced(
+        "--mode=CREATE",
+        "--name=Jim Doe",
+        "--email=jim.doe@example.com",
+        "NewRegistrar");
+    RegistrarContact registrarContact =
+        Registrar.loadByClientId("NewRegistrar").getContacts().asList().get(1);
+    assertThat(registrarContact.getTypes()).isEmpty();
+  }
+
   @Test
   public void testCreate_syncingRequiredSetToTrue() throws Exception {
     persistResource(