diff --git a/fsl/version.py b/fsl/version.py
index 4cad9f591ca222583b3f3587807ce95fbaf5798b..d40259f541448c9137101a2669c6adfd55cf14f9 100644
--- a/fsl/version.py
+++ b/fsl/version.py
@@ -47,7 +47,7 @@ import            re
 import            string
 
 
-__version__ = '3.20.0.dev0'
+__version__ = '3.21.0.dev0'
 """Current version number, as a string. """