bump version number
diff --git a/appveyor.yml b/appveyor.yml
index 5847ea9..0e81ba4 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -19,7 +19,7 @@
 
 # build Apache Thrift on AppVeyor - https://ci.appveyor.com
 
-version: '0.20.0.{build}'
+version: '0.21.0.{build}'
 
 shallow_clone: true