diff --git a/java/google/registry/flows/domain/DomainCheckFlow.java b/java/google/registry/flows/domain/DomainCheckFlow.java
index 1a3688187..e42d27af5 100644
--- a/java/google/registry/flows/domain/DomainCheckFlow.java
+++ b/java/google/registry/flows/domain/DomainCheckFlow.java
@@ -98,7 +98,7 @@ public final class DomainCheckFlow implements Flow {
    * The TLD states during which we want to report a domain with pending applications as
    * unavailable.
    */
-  private static final Set<TldState> PENDING_ALLOCATION_TLD_STATES =
+  private static final ImmutableSet<TldState> PENDING_ALLOCATION_TLD_STATES =
       Sets.immutableEnumSet(TldState.GENERAL_AVAILABILITY, TldState.QUIET_PERIOD);
 
   @Inject ResourceCommand resourceCommand;
diff --git a/java/google/registry/model/domain/launch/LaunchPhase.java b/java/google/registry/model/domain/launch/LaunchPhase.java
index ed8292755..3c1c3f226 100644
--- a/java/google/registry/model/domain/launch/LaunchPhase.java
+++ b/java/google/registry/model/domain/launch/LaunchPhase.java
@@ -22,7 +22,6 @@ import static java.util.Objects.hash;
 import com.google.common.collect.ImmutableMap;
 import com.googlecode.objectify.annotation.Embed;
 import google.registry.model.ImmutableObject;
-import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Objects;
 import javax.xml.bind.annotation.XmlAttribute;
@@ -64,7 +63,7 @@ public class LaunchPhase extends ImmutableObject {
   /** A custom server launch phase that is defined using the "name" attribute. */
   public static final LaunchPhase CUSTOM = create("custom", null);
 
-  private static final Map<String, LaunchPhase> LAUNCH_PHASES = initEnumMapping();
+  private static final ImmutableMap<String, LaunchPhase> LAUNCH_PHASES = initEnumMapping();
 
   /**
    * Returns a map of the static final fields to their values, case-converted.