diff --git a/lib/compiler/asts.js b/lib/compiler/asts.js
index 559e75d..f87702d 100644
--- a/lib/compiler/asts.js
+++ b/lib/compiler/asts.js
@@ -1,16 +1,27 @@
 "use strict";
 
-let arrays  = require("../utils/arrays"),
-    visitor = require("./visitor");
+let visitor = require("./visitor");
 
 /* AST utilities. */
 let asts = {
   findRule: function(ast, name) {
-    return arrays.find(ast.rules, r => r.name === name);
+    for (let i = 0; i < ast.rules.length; i++) {
+      if (ast.rules[i].name === name) {
+        return ast.rules[i];
+      }
+    }
+
+    return undefined;
   },
 
   indexOfRule: function(ast, name) {
-    return arrays.indexOf(ast.rules, r => r.name === name);
+    for (let i = 0; i < ast.rules.length; i++) {
+      if (ast.rules[i].name === name) {
+        return i;
+      }
+    }
+
+    return -1;
   },
 
   alwaysConsumesOnSuccess: function(ast, node) {