diff --git a/src/PIL/version.py b/src/PIL/version.py
index f8f2a9841..fbf87ab58 100644
--- a/src/PIL/version.py
+++ b/src/PIL/version.py
@@ -1,2 +1,2 @@
 # Master version for Pillow
-__version__ = '5.0.0'
+__version__ = '5.1.0.dev0'