diff --git a/lib/module.js b/lib/module.js
index 1b9c2413b7..77675fcd98 100644
--- a/lib/module.js
+++ b/lib/module.js
@@ -165,10 +165,11 @@ Module._findPath = function(request, paths, isMain) {
     return false;
   }
 
-  const cacheKey = JSON.stringify({request: request, paths: paths});
-  if (Module._pathCache[cacheKey]) {
-    return Module._pathCache[cacheKey];
-  }
+  var cacheKey = request + '\x00' +
+                (paths.length === 1 ? paths[0] : paths.join('\x00'));
+  var entry = Module._pathCache[cacheKey];
+  if (entry)
+    return entry;
 
   var exts;
   var trailingSlash = request.length > 0 &&