diff --git a/ext/tk/ChangeLog.tkextlib b/ext/tk/ChangeLog.tkextlib
index fa5524da01..fad15e8822 100644
--- a/ext/tk/ChangeLog.tkextlib
+++ b/ext/tk/ChangeLog.tkextlib
@@ -1,3 +1,9 @@
+2006-08-31  Hidetoshi NAGAI  <nagai@ai.kyutech.ac.jp>
+
+	* lib/tkextlib/blt.rb: double dashes (--) option doesn't work
+	  properly on some versions of BLT (wrong description on the
+	  manual of `blt::bgexec'?).
+
 2005-12-11  Hidetoshi NAGAI  <nagai@ai.kyutech.ac.jp>
 
 	* lib/tkextlib/SUPPORT_STATUS: update to support libraries in
diff --git a/ext/tk/lib/tkextlib/blt.rb b/ext/tk/lib/tkextlib/blt.rb
index 8ac8605513..115eb927ba 100644
--- a/ext/tk/lib/tkextlib/blt.rb
+++ b/ext/tk/lib/tkextlib/blt.rb
@@ -68,7 +68,7 @@ module Tk
 
       params.concat(hash_kv(args.shift, true)) if args[0].kind_of?(Hash)
 
-      params << '--'
+      params << '--' if args[0] =~ /^\s*-[^-]/
       params.concat(args)
 
       tk_call('::blt::bgexec', *params)
@@ -85,7 +85,7 @@ module Tk
 
       params.concat(hash_kv(args.shift, true)) if args[0].kind_of?(Hash)
 
-      params << '--'
+      params << '--' if args[0] =~ /^\s*-[^-]/
       params.concat(args)
       params << '&'