diff --git a/lib/nopt.js b/lib/nopt.js
index 97707e7..94a983c 100644
--- a/lib/nopt.js
+++ b/lib/nopt.js
@@ -246,12 +246,12 @@ function parse (args, data, remain, types, shorthands) {
     }
     var hadEq = false
     if (arg.charAt(0) === "-" && arg.length > 1) {
-      if (arg.indexOf("=") !== -1) {
+      var at = arg.indexOf('=')
+      if (at > -1) {
         hadEq = true
-        var v = arg.split("=")
-        arg = v.shift()
-        v = v.join("=")
-        args.splice.apply(args, [i, 1].concat([arg, v]))
+        var v = arg.substr(at + 1)
+        arg = arg.substr(0, at)
+        args.splice(i, 1, arg, v)
       }
 
       // see if it's a shorthand