diff --git a/lib/javascript/gflib.js b/lib/javascript/gflib.js
index faf7b1d69..728655469 100644
--- a/lib/javascript/gflib.js
+++ b/lib/javascript/gflib.js
@@ -97,6 +97,9 @@ Fun.prototype.isComplete = function() {
 		return true;
 	}
 } ;
+Fun.prototype.isLiteral = function() {
+  return (/^[\"\d]/).test(this.name);
+} ;
 
 /* Concrete syntax terms */
 
@@ -279,7 +282,14 @@ function GFConcrete(flags, rules, parser) {
 		this.parser = undefined;
 	}
 }
-GFConcrete.prototype.rule = function (name, cs) { return this.rules[name](cs); };
+GFConcrete.prototype.rule = function (name, cs) { 
+  var r = this.rules[name];
+  if (r) {
+    return this.rules[name](cs); 
+  } else {
+    window.alert("Missing rule " + name);
+  }
+};
 GFConcrete.prototype.addRule = function (name, f) { this.rules[name] = f; };
 GFConcrete.prototype.lindef = function (cat, v) {	return this.rules[cat]([new Str(v)]); } ;
 GFConcrete.prototype.linearize = function (tree) { 
@@ -297,8 +307,11 @@ GFConcrete.prototype.linearizeToTerm = function (tree) {
 		for (var i in tree.args) {
 		  cs.push(this.linearizeToTerm(tree.args[i]));
 		}
-		var newTerm = this.rule(tree.name, cs);
-		return newTerm;
+                if (tree.isLiteral()) {
+		  return new Arr(new Str(tree.name));
+		} else {
+		  return this.rule(tree.name, cs);
+		}
 	}
 };
 GFConcrete.prototype.unlex = function (ts) {