1 files changed, 11 insertions, 1 deletions
diff --git a/ext/win32ole/win32ole.gemspec b/ext/win32ole/win32ole.gemspec
index b6ea8e8a55..9c137a5d70 100644
--- a/ext/win32ole/win32ole.gemspec
+++ b/ext/win32ole/win32ole.gemspec
@@ -1,6 +1,16 @@
+source_version = ["", "ext/win32ole/"].find do |dir|
+  begin
+    break File.open(File.join(__dir__, "#{dir}win32ole.c")) {|f|
+      f.gets("\n#define WIN32OLE_VERSION ")
+      f.gets[/\s*"(.+)"/, 1]
+    }
+  rescue Errno::ENOENT
+  end
+end
+
 Gem::Specification.new do |spec|
   spec.name          = "win32ole"
-  spec.version       = "1.8.9"
+  spec.version       = source_version
   spec.authors       = ["Masaki Suketa"]
   spec.email         = ["suke@ruby-lang.org"]