diff --git a/lib/src/impl.dart b/lib/src/impl.dart
index a2b3e7f..9a8c2a0 100644
--- a/lib/src/impl.dart
+++ b/lib/src/impl.dart
@@ -115,7 +115,11 @@
     File f = new File(path.join(directory.path, 'pubspec.yaml'));
     if (f.existsSync()) {
       Map pubspec = yaml.loadYaml(f.readAsStringSync());
-      _version = new Version.parse(pubspec['version']);
+      if (pubspec['version'] == null) {
+        _version = Version.none;
+      } else {
+        _version = new Version.parse(pubspec['version']);
+      }
     }
   }