diff --git a/services/sync/modules/engines/clients.js b/services/sync/modules/engines/clients.js
index f423242c9ac..7d55cded58f 100644
--- a/services/sync/modules/engines/clients.js
+++ b/services/sync/modules/engines/clients.js
@@ -49,7 +49,9 @@ ClientEngine.prototype = {
   _trackerObj: ClientsTracker,
 
   // Always sync client data as it controls other sync behavior
-  get enabled() true,
+  get enabled() {
+    return true;
+  },
 
   get lastRecordUpload() {
     return Svc.Prefs.get(this.name + ".lastRecordUpload", 0);
@@ -102,7 +104,9 @@ ClientEngine.prototype = {
     let localID = Svc.Prefs.get("client.GUID", "");
     return localID == "" ? this.localID = Utils.makeGUID() : localID;
   },
-  set localID(value) Svc.Prefs.set("client.GUID", value),
+  set localID(value) {
+    Svc.Prefs.set("client.GUID", value);
+  },
 
   get brandName() {
     let brand = new StringBundle("chrome://branding/locale/brand.properties");
@@ -116,10 +120,16 @@ ClientEngine.prototype = {
 
     return this.localName = Utils.getDefaultDeviceName();
   },
-  set localName(value) Svc.Prefs.set("client.name", value),
+  set localName(value) {
+    Svc.Prefs.set("client.name", value);
+  },
 
-  get localType() Svc.Prefs.get("client.type", "desktop"),
-  set localType(value) Svc.Prefs.set("client.type", value),
+  get localType() {
+    return Svc.Prefs.get("client.type", "desktop");
+  },
+  set localType(value) {
+    Svc.Prefs.set("client.type", value);
+  },
 
   isMobile: function isMobile(id) {
     if (this._store._remoteClients[id])
diff --git a/services/sync/modules/engines/forms.js b/services/sync/modules/engines/forms.js
index a139280b31e..84e46de622c 100644
--- a/services/sync/modules/engines/forms.js
+++ b/services/sync/modules/engines/forms.js
@@ -109,7 +109,9 @@ FormEngine.prototype = {
 
   syncPriority: 6,
 
-  get prefName() "history",
+  get prefName() {
+    return "history";
+  },
 
   _findDupe: function _findDupe(item) {
     return FormWrapper.getGUID(item.name, item.value);
diff --git a/services/sync/modules/main.js b/services/sync/modules/main.js
index f59beb184d7..e8e705e726a 100644
--- a/services/sync/modules/main.js
+++ b/services/sync/modules/main.js
@@ -15,12 +15,14 @@ var lazies = {
 };
 
 function lazyImport(module, dest, props) {
-  function getter(prop) function() {
-    let ns = {};
-    Components.utils.import(module, ns);
-    delete dest[prop];
-    return dest[prop] = ns[prop];
-  };
+  function getter(prop) {
+    return function() {
+      let ns = {};
+      Components.utils.import(module, ns);
+      delete dest[prop];
+      return dest[prop] = ns[prop];
+    };
+  }
   props.forEach(function (prop) { dest.__defineGetter__(prop, getter(prop)); });
 }
 
diff --git a/services/sync/modules/policies.js b/services/sync/modules/policies.js
index fbc547d1073..e940f3febb3 100644
--- a/services/sync/modules/policies.js
+++ b/services/sync/modules/policies.js
@@ -61,20 +61,40 @@ SyncScheduler.prototype = {
   },
 
   // nextSync is in milliseconds, but prefs can't hold that much
-  get nextSync() Svc.Prefs.get("nextSync", 0) * 1000,
-  set nextSync(value) Svc.Prefs.set("nextSync", Math.floor(value / 1000)),
+  get nextSync() {
+    return Svc.Prefs.get("nextSync", 0) * 1000;
+  },
+  set nextSync(value) {
+    Svc.Prefs.set("nextSync", Math.floor(value / 1000));
+  },
 
-  get syncInterval() Svc.Prefs.get("syncInterval", this.singleDeviceInterval),
-  set syncInterval(value) Svc.Prefs.set("syncInterval", value),
+  get syncInterval() {
+    return Svc.Prefs.get("syncInterval", this.singleDeviceInterval);
+  },
+  set syncInterval(value) {
+    Svc.Prefs.set("syncInterval", value);
+  },
 
-  get syncThreshold() Svc.Prefs.get("syncThreshold", SINGLE_USER_THRESHOLD),
-  set syncThreshold(value) Svc.Prefs.set("syncThreshold", value),
+  get syncThreshold() {
+    return Svc.Prefs.get("syncThreshold", SINGLE_USER_THRESHOLD);
+  },
+  set syncThreshold(value) {
+    Svc.Prefs.set("syncThreshold", value);
+  },
 
-  get globalScore() Svc.Prefs.get("globalScore", 0),
-  set globalScore(value) Svc.Prefs.set("globalScore", value),
+  get globalScore() {
+    return Svc.Prefs.get("globalScore", 0);
+  },
+  set globalScore(value) {
+    Svc.Prefs.set("globalScore", value);
+  },
 
-  get numClients() Svc.Prefs.get("numClients", 0),
-  set numClients(value) Svc.Prefs.set("numClients", value),
+  get numClients() {
+    return Svc.Prefs.get("numClients", 0);
+  },
+  set numClients(value) {
+    Svc.Prefs.set("numClients", value);
+  },
 
   init: function init() {
     this._log.level = Log.Level[Svc.Prefs.get("log.logger.service.main")];
diff --git a/services/sync/modules/record.js b/services/sync/modules/record.js
index 71a6b4083f6..43e452a4100 100644
--- a/services/sync/modules/record.js
+++ b/services/sync/modules/record.js
@@ -196,7 +196,9 @@ CryptoWrapper.prototype = {
   },
 
   // The custom setter below masks the parent's getter, so explicitly call it :(
-  get id() WBORecord.prototype.__lookupGetter__("id").call(this),
+  get id() {
+    return WBORecord.prototype.__lookupGetter__("id").call(this);
+  },
 
   // Keep both plaintext and encrypted versions of the id to verify integrity
   set id(val) {
@@ -356,8 +358,9 @@ CollectionKeyManager.prototype = {
   /**
    * Create a WBO for the current keys.
    */
-  asWBO: function(collection, id)
-    this._makeWBO(this._collections, this._default),
+  asWBO: function(collection, id) {
+    return this._makeWBO(this._collections, this._default);
+  },
 
   /**
    * Compute a new default key, and new keys for any specified collections.
@@ -560,14 +563,14 @@ Collection.prototype = {
   },
 
   // Apply the action to a certain set of ids
-  get ids() this._ids,
+  get ids() { return this._ids; },
   set ids(value) {
     this._ids = value;
     this._rebuildURL();
   },
 
   // Limit how many records to get
-  get limit() this._limit,
+  get limit() { return this._limit; },
   set limit(value) {
     this._limit = value;
     this._rebuildURL();
diff --git a/services/sync/modules/resource.js b/services/sync/modules/resource.js
index 9bacb3491a9..84cc99f8d71 100644
--- a/services/sync/modules/resource.js
+++ b/services/sync/modules/resource.js
@@ -134,7 +134,9 @@ AsyncResource.prototype = {
   //
   // Get and set the data encapulated in the resource.
   _data: null,
-  get data() this._data,
+  get data() {
+    return this._data;
+  },
   set data(value) {
     this._data = value;
   },
diff --git a/services/sync/modules/service.js b/services/sync/modules/service.js
index 43b1d979c9f..9c7dd0321a7 100644
--- a/services/sync/modules/service.js
+++ b/services/sync/modules/service.js
@@ -79,7 +79,9 @@ Sync11Service.prototype = {
   metaURL: null,
   cryptoKeyURL: null,
 
-  get serverURL() Svc.Prefs.get("serverURL"),
+  get serverURL() {
+    return Svc.Prefs.get("serverURL");
+  },
   set serverURL(value) {
     if (!value.endsWith("/")) {
       value += "/";
@@ -94,7 +96,9 @@ Sync11Service.prototype = {
     Svc.Prefs.reset("clusterURL");
   },
 
-  get clusterURL() Svc.Prefs.get("clusterURL", ""),
+  get clusterURL() {
+    return Svc.Prefs.get("clusterURL", "");
+  },
   set clusterURL(value) {
     Svc.Prefs.set("clusterURL", value);
     this._updateCachedURLs();
diff --git a/services/sync/modules/util.js b/services/sync/modules/util.js
index 85f67d78ae2..a43d506884e 100644
--- a/services/sync/modules/util.js
+++ b/services/sync/modules/util.js
@@ -477,7 +477,7 @@ this.Utils = {
 
     // 20-char sync key.
     if (pp.length == 23 &&
-        [5, 11, 17].every(function(i) pp[i] == '-')) {
+        [5, 11, 17].every(i => pp[i] == '-')) {
 
       return pp.slice(0, 5) + pp.slice(6, 11)
              + pp.slice(12, 17) + pp.slice(18, 23);
@@ -485,7 +485,7 @@ this.Utils = {
 
     // "Modern" 26-char key.
     if (pp.length == 31 &&
-        [1, 7, 13, 19, 25].every(function(i) pp[i] == '-')) {
+        [1, 7, 13, 19, 25].every(i => pp[i] == '-')) {
 
       return pp.slice(0, 1) + pp.slice(2, 7)
              + pp.slice(8, 13) + pp.slice(14, 19)
diff --git a/services/sync/tests/unit/test_bookmark_legacy_microsummaries_support.js b/services/sync/tests/unit/test_bookmark_legacy_microsummaries_support.js
index a7e3a46477f..207372ed68c 100644
--- a/services/sync/tests/unit/test_bookmark_legacy_microsummaries_support.js
+++ b/services/sync/tests/unit/test_bookmark_legacy_microsummaries_support.js
@@ -85,12 +85,12 @@ function run_test() {
   do_check_eq(PlacesUtils.bookmarks.getKeywordForBookmark(id), null);
 
   do_check_throws(
-    function () PlacesUtils.annotations.getItemAnnotation(id, GENERATORURI_ANNO),
+    () => PlacesUtils.annotations.getItemAnnotation(id, GENERATORURI_ANNO),
     Cr.NS_ERROR_NOT_AVAILABLE
   );
 
   do_check_throws(
-    function () PlacesUtils.annotations.getItemAnnotation(id, STATICTITLE_ANNO),
+    () => PlacesUtils.annotations.getItemAnnotation(id, STATICTITLE_ANNO),
     Cr.NS_ERROR_NOT_AVAILABLE
   );
 
diff --git a/services/sync/tests/unit/test_corrupt_keys.js b/services/sync/tests/unit/test_corrupt_keys.js
index 2db080a8f80..cce01636170 100644
--- a/services/sync/tests/unit/test_corrupt_keys.js
+++ b/services/sync/tests/unit/test_corrupt_keys.js
@@ -51,7 +51,7 @@ add_task(function test_locally_changed_keys() {
                           }]}]};
     delete Svc.Session;
     Svc.Session = {
-      getBrowserState: function () JSON.stringify(myTabs)
+      getBrowserState: () => JSON.stringify(myTabs)
     };
 
     setBasicCredentials("johndoe", "password", passphrase);
diff --git a/services/sync/tests/unit/test_service_detect_upgrade.js b/services/sync/tests/unit/test_service_detect_upgrade.js
index 528bd751b13..0f46832d983 100644
--- a/services/sync/tests/unit/test_service_detect_upgrade.js
+++ b/services/sync/tests/unit/test_service_detect_upgrade.js
@@ -60,7 +60,7 @@ add_test(function v4_upgrade() {
                           }]}]};
     delete Svc.Session;
     Svc.Session = {
-      getBrowserState: function () JSON.stringify(myTabs)
+      getBrowserState: () => JSON.stringify(myTabs)
     };
 
     Service.status.resetSync();
@@ -229,7 +229,7 @@ add_test(function v5_upgrade() {
                           }]}]};
     delete Svc.Session;
     Svc.Session = {
-      getBrowserState: function () JSON.stringify(myTabs)
+      getBrowserState: () => JSON.stringify(myTabs)
     };
 
     Service.status.resetSync();
diff --git a/services/sync/tests/unit/test_service_sync_updateEnabledEngines.js b/services/sync/tests/unit/test_service_sync_updateEnabledEngines.js
index ffc631dd5f8..5192e694d07 100644
--- a/services/sync/tests/unit/test_service_sync_updateEnabledEngines.js
+++ b/services/sync/tests/unit/test_service_sync_updateEnabledEngines.js
@@ -41,7 +41,9 @@ function StirlingEngine() {
 StirlingEngine.prototype = {
   __proto__: SteamEngine.prototype,
   // This engine's enabled state is the same as the SteamEngine's.
-  get prefName() "steam"
+  get prefName() {
+    return "steam";
+  }
 };
 Service.engineManager.register(StirlingEngine);
 
diff --git a/services/sync/tests/unit/test_tab_tracker.js b/services/sync/tests/unit/test_tab_tracker.js
index 620ea07e58a..f0bff3cc91d 100644
--- a/services/sync/tests/unit/test_tab_tracker.js
+++ b/services/sync/tests/unit/test_tab_tracker.js
@@ -15,7 +15,9 @@ function fakeSvcWinMediator() {
     getEnumerator: function() {
       return {
         cnt: 2,
-        hasMoreElements: function() this.cnt-- > 0,
+        hasMoreElements: function() {
+          return this.cnt-- > 0;
+        },
         getNext: function() {
           let elt = {addTopics: [], remTopics: []};
           logs.push(elt);
diff --git a/services/sync/tests/unit/test_utils_catch.js b/services/sync/tests/unit/test_utils_catch.js
index a10e5eb0d80..302e20e2c31 100644
--- a/services/sync/tests/unit/test_utils_catch.js
+++ b/services/sync/tests/unit/test_utils_catch.js
@@ -15,31 +15,39 @@ function run_test() {
       }
     },
 
-    func: function() this.catch(function() {
-      rightThis = this == obj;
-      didCall = true;
-      return 5;
-    })(),
+    func: function() {
+      return this.catch(function() {
+        rightThis = this == obj;
+        didCall = true;
+        return 5;
+      })();
+    },
 
-    throwy: function() this.catch(function() {
-      rightThis = this == obj;
-      didCall = true;
-      throw 10;
-    })(),
+    throwy: function() {
+      return this.catch(function() {
+        rightThis = this == obj;
+        didCall = true;
+        throw 10;
+      })();
+    },
 
-    callbacky: function() this.catch(function() {
-      rightThis = this == obj;
-      didCall = true;
-      throw 10;
-    }, function(ex) {
-      wasTen = (ex == 10)
-    })(),
+    callbacky: function() {
+      return this.catch(function() {
+        rightThis = this == obj;
+        didCall = true;
+        throw 10;
+      }, function(ex) {
+        wasTen = (ex == 10)
+      })();
+    },
 
-    lockedy: function() this.catch(function() {
-      rightThis = this == obj;
-      didCall = true;
-      throw("Could not acquire lock.");
-    })()
+    lockedy: function() {
+      return this.catch(function() {
+        rightThis = this == obj;
+        didCall = true;
+        throw("Could not acquire lock.");
+      })();
+    }
   };
 
   _("Make sure a normal call will call and return");
diff --git a/services/sync/tests/unit/test_utils_deferGetSet.js b/services/sync/tests/unit/test_utils_deferGetSet.js
index 55c0fcb0e67..9d58a9873e3 100644
--- a/services/sync/tests/unit/test_utils_deferGetSet.js
+++ b/services/sync/tests/unit/test_utils_deferGetSet.js
@@ -6,8 +6,12 @@ function run_test() {
   base.prototype = {
     dst: {},
 
-    get a() "a",
-    set b(val) this.dst.b = val + "!!!"
+    get a() {
+      return "a";
+    },
+    set b(val) {
+      this.dst.b = val + "!!!";
+    }
   };
   let src = new base();
 
diff --git a/services/sync/tests/unit/test_utils_lock.js b/services/sync/tests/unit/test_utils_lock.js
index fd8a4b1f522..d1830787e63 100644
--- a/services/sync/tests/unit/test_utils_lock.js
+++ b/services/sync/tests/unit/test_utils_lock.js
@@ -27,19 +27,23 @@ function run_test() {
       this._locked = false;
     },
 
-    func: function() this._lock("Test utils lock",
-    function() {
-      rightThis = this == obj;
-      didCall = true;
-      return 5;
-    })(),
+    func: function() {
+      return this._lock("Test utils lock",
+                        function() {
+                          rightThis = this == obj;
+                          didCall = true;
+                          return 5;
+                        })();
+    },
 
-    throwy: function() this._lock("Test utils lock throwy",
-    function() {
-      rightThis = this == obj;
-      didCall = true;
-      this.throwy();
-    })()
+    throwy: function() {
+      return this._lock("Test utils lock throwy",
+                        function() {
+                          rightThis = this == obj;
+                          didCall = true;
+                          this.throwy();
+                        })();
+    }
   };
 
   _("Make sure a normal call will call and return");
diff --git a/services/sync/tests/unit/test_utils_notify.js b/services/sync/tests/unit/test_utils_notify.js
index c191bbfef67..5bd38da5f27 100644
--- a/services/sync/tests/unit/test_utils_notify.js
+++ b/services/sync/tests/unit/test_utils_notify.js
@@ -9,17 +9,21 @@ function run_test() {
       trace: function() {}
     },
 
-    func: function() this.notify("bar", "baz", function() {
-      rightThis = this == obj;
-      didCall = true;
-      return 5;
-    })(),
+    func: function() {
+      return this.notify("bar", "baz", function() {
+        rightThis = this == obj;
+        didCall = true;
+        return 5;
+      })();
+    },
 
-    throwy: function() this.notify("bad", "one", function() {
-      rightThis = this == obj;
-      didCall = true;
-      throw 10;
-    })()
+    throwy: function() {
+      return this.notify("bad", "one", function() {
+        rightThis = this == obj;
+        didCall = true;
+        throw 10;
+      })();
+    }
   };
 
   let state = 0;