1 files changed, 2 insertions, 0 deletions
diff --git a/lib/zlib.js b/lib/zlib.js
index 2acde58fd4..724f9a37b6 100644
--- a/lib/zlib.js
+++ b/lib/zlib.js
@@ -19,6 +19,8 @@
 // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
+'use strict';
+
 var Transform = require('_stream_transform');
 
 var binding = process.binding('zlib');