diff --git a/src/main/java/org/mozilla/gecko/fxa/login/FxAccountLoginStateMachine.java b/src/main/java/org/mozilla/gecko/fxa/login/FxAccountLoginStateMachine.java
index 84b16d8b2..34e507541 100644
--- a/src/main/java/org/mozilla/gecko/fxa/login/FxAccountLoginStateMachine.java
+++ b/src/main/java/org/mozilla/gecko/fxa/login/FxAccountLoginStateMachine.java
@@ -5,7 +5,7 @@
 package org.mozilla.gecko.fxa.login;
 
 import java.security.NoSuchAlgorithmException;
-import java.util.HashSet;
+import java.util.EnumSet;
 import java.util.Set;
 
 import org.mozilla.gecko.background.fxa.FxAccountClient;
@@ -29,7 +29,7 @@ public static class ExecuteDelegate {
     protected final LoginStateMachineDelegate delegate;
     protected final StateLabel desiredStateLabel;
     // It's as difficult to detect arbitrary cycles as repeated states.
-    protected final Set<StateLabel> stateLabelsSeen = new HashSet<StateLabel>();
+    protected final Set<StateLabel> stateLabelsSeen = EnumSet.noneOf(StateLabel.class);
 
     protected ExecuteDelegate(StateLabel initialStateLabel, StateLabel desiredStateLabel, LoginStateMachineDelegate delegate) {
       this.delegate = delegate;
diff --git a/src/main/java/org/mozilla/gecko/fxa/sync/FxAccountGlobalSession.java b/src/main/java/org/mozilla/gecko/fxa/sync/FxAccountGlobalSession.java
index fdeb18dbb..674668559 100644
--- a/src/main/java/org/mozilla/gecko/fxa/sync/FxAccountGlobalSession.java
+++ b/src/main/java/org/mozilla/gecko/fxa/sync/FxAccountGlobalSession.java
@@ -7,7 +7,9 @@
 import java.io.IOException;
 import java.net.URISyntaxException;
 import java.util.Collections;
+import java.util.EnumMap;
 import java.util.HashMap;
+import java.util.Map;
 
 import org.json.simple.parser.ParseException;
 import org.mozilla.gecko.sync.GlobalSession;
@@ -34,7 +36,7 @@ public FxAccountGlobalSession(SyncConfiguration config,
   @Override
   public void prepareStages() {
     super.prepareStages();
-    HashMap<Stage, GlobalSyncStage> stages = new HashMap<Stage, GlobalSyncStage>();
+    Map<Stage, GlobalSyncStage> stages = new EnumMap<>(Stage.class);
     stages.putAll(this.stages);
     stages.put(Stage.ensureClusterURL, new CheckPreconditionsStage());
     this.stages = Collections.unmodifiableMap(stages);
diff --git a/src/main/java/org/mozilla/gecko/sync/GlobalSession.java b/src/main/java/org/mozilla/gecko/sync/GlobalSession.java
index ab3302ce6..fddeedf29 100644
--- a/src/main/java/org/mozilla/gecko/sync/GlobalSession.java
+++ b/src/main/java/org/mozilla/gecko/sync/GlobalSession.java
@@ -10,6 +10,7 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.EnumMap;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
@@ -174,7 +175,7 @@ public void executeCommand(final GlobalSession session, List<String> args) {
   }
 
   protected void prepareStages() {
-    HashMap<Stage, GlobalSyncStage> stages = new HashMap<Stage, GlobalSyncStage>();
+    Map<Stage, GlobalSyncStage> stages = new EnumMap<Stage, GlobalSyncStage>(Stage.class);
 
     stages.put(Stage.checkPreconditions,      new CheckPreconditionsStage());
     stages.put(Stage.ensureClusterURL,        new EnsureClusterURLStage(nodeAssignmentCallback));