diff --git a/pom.xml b/pom.xml
index 8c2577e..4baba32 100644
--- a/pom.xml
+++ b/pom.xml
@@ -2,7 +2,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.github.nkzawa</groupId>
   <artifactId>socket.io-client</artifactId>
-  <version>0.3.1-SNAPSHOT</version>
+  <version>0.4.0-SNAPSHOT</version>
   <packaging>jar</packaging>
   <name>socket.io-client</name>
   <description>Socket.IO Client Library for Java</description>