diff --git a/Gemfile.lock b/Gemfile.lock
index 7f78cb766..cc87f40f6 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,7 +1,7 @@
 PATH
   remote: .
   specs:
-    rbs (3.8.1)
+    rbs (3.9.0.dev)
       logger
 
 PATH
diff --git a/lib/rbs/version.rb b/lib/rbs/version.rb
index 1105fc20e..53c344a4d 100644
--- a/lib/rbs/version.rb
+++ b/lib/rbs/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module RBS
-  VERSION = "3.8.1"
+  VERSION = "3.9.0.dev"
 end