diff --git a/src/runtime/javascript/minibar/pgf_online.js b/src/runtime/javascript/minibar/pgf_online.js
index 2f46032e3..ac6620ee5 100644
--- a/src/runtime/javascript/minibar/pgf_online.js
+++ b/src/runtime/javascript/minibar/pgf_online.js
@@ -17,10 +17,7 @@ function pgf_online(options) {
 	    http_get_json(this.grammars_url+"grammars.cgi",cont);
 	},
 	pgf_call: function(cmd,args,cont) {
-	    var url=this.current_grammar_url+"?command="+cmd;
-	    for(var arg in args)
-		if(args[arg]!=undefined)
-		    url+="&"+arg+"="+encodeURIComponent(args[arg]);
+	    var url=this.current_grammar_url+"?command="+cmd+encodeArgs(args)
 	    http_get_json(url,cont);
 	},
 	
diff --git a/src/runtime/javascript/minibar/support.js b/src/runtime/javascript/minibar/support.js
index 743ace3de..c65c1a389 100644
--- a/src/runtime/javascript/minibar/support.js
+++ b/src/runtime/javascript/minibar/support.js
@@ -112,6 +112,15 @@ function http_get_json(url,cont) {
     else jsonpf(url,cont);
 }
 
+/* --- URL construction ----------------------------------------------------- */
+
+function encodeArgs(args) {
+    var q=""
+    for(var arg in args)
+	if(args[arg]!=undefined)
+	    q+="&"+arg+"="+encodeURIComponent(args[arg]);
+    return q;
+}
 
 /* --- HTML construction ---------------------------------------------------- */
 function text(s) { return document.createTextNode(s); }