diff --git a/version.py b/version.py
index 941dd14..97f0129 100644
--- a/version.py
+++ b/version.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-version = '3.4.0a1'
+version = '4.0.0'
 
 required_versions = {'toil': '>=3.12.0',
                      'pyyaml': '>=3.11'}