diff --git a/lib/recaptcha.js b/lib/recaptcha.js
index 17f2555..4fa061a 100644
--- a/lib/recaptcha.js
+++ b/lib/recaptcha.js
@@ -70,8 +70,8 @@ Recaptcha.prototype.toHTML = function() {
         query_string += '&error=' + this.error_code;
     }
 
-    var script_src = (this.is_secure ? "https://" : "http://") + SCRIPT_SRC + '?' + query_string;
-    var noscript_src = (this.is_secure ? "https://" : "http://") + NOSCRIPT_SRC + '?' + query_string;
+    var script_src = "//" + SCRIPT_SRC + '?' + query_string;
+    var noscript_src = "//" + NOSCRIPT_SRC + '?' + query_string;
 
     return '<script type="text/javascript" src="' + script_src + '"></script>' +
            '<noscript><iframe src="' + noscript_src + '" height="300" width="500" ' +