diff --git a/platformio/__init__.py b/platformio/__init__.py
index 1e2e3fd1..92359835 100644
--- a/platformio/__init__.py
+++ b/platformio/__init__.py
@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-VERSION = (4, 3, 4)
+VERSION = (4, 3, "5a1")
 __version__ = ".".join([str(s) for s in VERSION])
 
 __title__ = "platformio"