diff --git a/base64.gemspec b/base64.gemspec
index daa0b7f..d793dce 100644
--- a/base64.gemspec
+++ b/base64.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          = "base64"
-  spec.version       = "0.1.1"
+  spec.name          = name
+  spec.version       = version
   spec.authors       = ["Yusuke Endoh"]
   spec.email         = ["mame@ruby-lang.org"]
 
diff --git a/lib/base64.rb b/lib/base64.rb
index 693aa1f..15c0b29 100644
--- a/lib/base64.rb
+++ b/lib/base64.rb
@@ -22,6 +22,9 @@
 # binary data into purely printable characters.
 
 module Base64
+
+  VERSION = "0.1.1"
+
   module_function
 
   # Returns the Base64-encoded version of +bin+.