diff --git a/qualtran/_version.py b/qualtran/_version.py
index 3515c859e..fe852a7ee 100644
--- a/qualtran/_version.py
+++ b/qualtran/_version.py
@@ -12,4 +12,4 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
-__version__ = "0.4.0.dev0"
+__version__ = "0.4.0"