diff --git a/lib/optparse.rb b/lib/optparse.rb
index ea6844b..dcd980f 100644
--- a/lib/optparse.rb
+++ b/lib/optparse.rb
@@ -426,7 +426,8 @@
 #
 class OptionParser
   # The version string
-  OptionParser::Version = "0.7.0.dev.2"
+  VERSION = "0.7.0.dev.2"
+  Version = VERSION # for compatibility
 
   # :stopdoc:
   NoArgument = [NO_ARGUMENT = :NONE, nil].freeze
diff --git a/optparse.gemspec b/optparse.gemspec
index 6ea6b88..885b0ec 100644
--- a/optparse.gemspec
+++ b/optparse.gemspec
@@ -3,7 +3,7 @@
 name = File.basename(__FILE__, ".gemspec")
 version = ["lib", Array.new(name.count("-")+1, "..").join("/")].find do |dir|
   break File.foreach(File.join(__dir__, dir, "#{name.tr('-', '/')}.rb")) do |line|
-    /^\s*OptionParser::Version\s*=\s*"(.*)"/ =~ line and break $1
+    /^\s*VERSION\s*=\s*"(.*)"/ =~ line and break $1
   end rescue nil
 end
 
diff --git a/rakelib/version.rake b/rakelib/version.rake
index 583530d..f33721f 100644
--- a/rakelib/version.rake
+++ b/rakelib/version.rake
@@ -6,7 +6,7 @@ class << (helper = Bundler::GemHelper.instance)
   def update_version
     File.open(mainfile, "r+b") do |f|
       d = f.read
-      if d.sub!(/^(\s*OptionParser::Version\s*=\s*)".*"/) {$1 + gemspec.version.to_s.dump}
+      if d.sub!(/^(\s*VERSION\s*=\s*)".*"/) {$1 + gemspec.version.to_s.dump}
         f.rewind
         f.truncate(0)
         f.print(d)