1 files changed, 2 insertions, 0 deletions
diff --git a/lib/assert.js b/lib/assert.js
index c83f977a25..a05a487288 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -22,6 +22,8 @@
 // ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
+'use strict';
+
 // UTILITY
 var util = require('util');
 var pSlice = Array.prototype.slice;