diff --git a/.bumpversion.cfg b/.bumpversion.cfg
index 51b5fc170c..79cd4c0592 100644
--- a/.bumpversion.cfg
+++ b/.bumpversion.cfg
@@ -1,9 +1,9 @@
 [bumpversion]
-current_version = 0.9.0a3.gamma0
+current_version = 0.9.0a4.dev0
 commit = True
 tag = False
 parse = (?P<major>\d+)\.(?P<minor>\d+)\.(?P<patch>\d+)((?P<pre>[a-z]+)(?P<num>\d+))?(\.(?P<release>dev)(?P<dev>\d+))?
-serialize = 
+serialize =
 	{major}.{minor}.{patch}{pre}{num}.{release}{dev}
 	{major}.{minor}.{patch}{pre}{num}
 	{major}.{minor}.{patch}.{release}{dev}
@@ -13,12 +13,12 @@ serialize =
 
 [bumpversion:part:release]
 optional_value = gamma
-values = 
+values =
 	dev
 	gamma
 
 [bumpversion:part:dev]
-values = 
+values =
 	0
 	1
 	2
@@ -28,9 +28,8 @@ optional_value = 4
 
 [bumpversion:part:pre]
 optional_value = final
-values = 
+values =
 	a
 	b
 	rc
 	final
-
diff --git a/satpy/version.py b/satpy/version.py
index 6fc8134325..fc83df757d 100644
--- a/satpy/version.py
+++ b/satpy/version.py
@@ -23,4 +23,4 @@
 """Version file.
 """
 
-__version__ = "0.9.0a3"
+__version__ = "0.9.0a4.dev0"