diff --git a/lib/prettyprint.rb b/lib/prettyprint.rb
index 188c2e6..540b12f 100644
--- a/lib/prettyprint.rb
+++ b/lib/prettyprint.rb
@@ -33,6 +33,8 @@
 #
 class PrettyPrint
 
+  VERSION = "0.1.1"
+
   # This is a convenience method which is same as follows:
   #
   #   begin
diff --git a/prettyprint.gemspec b/prettyprint.gemspec
index eae2227..a18adb1 100644
--- a/prettyprint.gemspec
+++ b/prettyprint.gemspec
@@ -1,6 +1,13 @@
+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*VERSION\s*=\s*"(.*)"/ =~ line and break $1
+  end rescue nil
+end
+
 Gem::Specification.new do |spec|
-  spec.name          = "prettyprint"
-  spec.version       = "0.1.1"
+  spec.name          = name
+  spec.version       = version
   spec.authors       = ["Tanaka Akira"]
   spec.email         = ["akr@fsij.org"]