diff --git a/lib/core/engine.js b/lib/core/engine.js
index 8139e2be9..e7aa45bad 100644
--- a/lib/core/engine.js
+++ b/lib/core/engine.js
@@ -146,7 +146,9 @@ class Engine {
         self.currentAbi = abi;
         self.contractsJSON = contractsJSON;
         pipeline.build(abi, contractsJSON, null, function() {
-          self.watch.restart(); // Necessary because changing a file while it is writing can stop it from being watched
+          if (self.watch) {
+            self.watch.restart(); // Necessary because changing a file while it is writing can stop it from being watched
+          }
           self.events.emit('outputDone');
         });
       });