diff --git a/.jshintrc b/.jshintrc
index 5e969bf..c7e08b0 100644
--- a/.jshintrc
+++ b/.jshintrc
@@ -46,5 +46,6 @@
 	"browser": true,
 	"phantom": true,
 	"node": true,
-	"esversion": 6
+	"esversion": 6,
+	"validthis": true
 }
diff --git a/benchmark/benchmark.js b/benchmark/benchmark.js
index 2c17d66..13bb190 100644
--- a/benchmark/benchmark.js
+++ b/benchmark/benchmark.js
@@ -1,3 +1,4 @@
+"use strict";
 /* jshint ignore:start */
 var b = require("steal-benchmark");
 var Observation = require("can-observation");
diff --git a/can-observation.js b/can-observation.js
index b649906..6d1cfa3 100644
--- a/can-observation.js
+++ b/can-observation.js
@@ -1,3 +1,4 @@
+"use strict";
 /* global require */
 // # can-observation
 var namespace = require('can-namespace');
diff --git a/recorder-dependency-helpers.js b/recorder-dependency-helpers.js
index aa4aa3d..bfaa18c 100644
--- a/recorder-dependency-helpers.js
+++ b/recorder-dependency-helpers.js
@@ -1,3 +1,4 @@
+"use strict";
 // # Recorder Dependency Helpers
 // This exposes two helpers:
 // - `updateObservations` - binds and unbinds a diff of two observation records
diff --git a/temporarily-bind.js b/temporarily-bind.js
index a93b213..e2f19b7 100644
--- a/temporarily-bind.js
+++ b/temporarily-bind.js
@@ -1,3 +1,4 @@
+"use strict";
 var canReflect = require("can-reflect");
 
 var temporarilyBoundNoOperation = function(){};