diff --git a/lib/dencli/cmd.rb b/lib/dencli/cmd.rb
index 0d214f5..9445514 100644
--- a/lib/dencli/cmd.rb
+++ b/lib/dencli/cmd.rb
@@ -167,15 +167,15 @@ class DenCli::CMD
 
 		def parse_opt_string opt
 			case opt
-			when /\A(--\[no-\][^=]+)\z/
+			when /\A(--\[no-\][^= ]+)\z/
 				@long, @val = $1, nil
-			when /\A(--[^=]+)=(.+)\z/
+			when /\A(--[^= ]+)[= ](.+)\z/
 				@long, @val = $1, $2 || @val
-			when /\A(--[^=]+)\z/
+			when /\A(--[^= ]+)\z/
 				@long, @val = $1, nil
-			when /\A(-[^=-])=?(.+)\z/
+			when /\A(-[^= -])[= ]?(.+)\z/
 				@short, @val = $1, $2 || @val
-			when /\A(-[^=-])\z/
+			when /\A(-[^= -])\z/
 				@short, @val = $1, nil
 			else
 				raise ArgumentError, "Unexpected format for option: #{opt.inspect}"