diff --git a/lib/async.js b/lib/async.js
index cf8c24b5..40227a1f 100644
--- a/lib/async.js
+++ b/lib/async.js
@@ -36,6 +36,14 @@ var maybeUnwrapSymlink = function maybeUnwrapSymlink(x, opts, cb) {
     }
 };
 
+var getPackageCandidates = function getPackageCandidates(x, start, opts) {
+    var dirs = nodeModulesPaths(start, opts, x);
+    for (var i = 0; i < dirs.length; i++) {
+        dirs[i] = path.join(dirs[i], x);
+    }
+    return dirs;
+};
+
 module.exports = function resolve(x, options, callback) {
     var cb = callback;
     var opts = options;
@@ -55,6 +63,7 @@ module.exports = function resolve(x, options, callback) {
     var isFile = opts.isFile || defaultIsFile;
     var isDirectory = opts.isDirectory || defaultIsDir;
     var readFile = opts.readFile || fs.readFile;
+    var packageIterator = opts.packageIterator;
 
     var extensions = opts.extensions || ['.js'];
     var basedir = opts.basedir || path.dirname(caller());
@@ -265,19 +274,18 @@ module.exports = function resolve(x, options, callback) {
         if (dirs.length === 0) return cb(null, undefined);
         var dir = dirs[0];
 
-        isDirectory(dir, isdir);
+        isDirectory(path.dirname(dir), isdir);
 
         function isdir(err, isdir) {
             if (err) return cb(err);
             if (!isdir) return processDirs(cb, dirs.slice(1));
-            var file = path.join(dir, x);
-            loadAsFile(file, opts.package, onfile);
+            loadAsFile(dir, opts.package, onfile);
         }
 
         function onfile(err, m, pkg) {
             if (err) return cb(err);
             if (m) return cb(null, m, pkg);
-            loadAsDirectory(path.join(dir, x), opts.package, ondir);
+            loadAsDirectory(dir, opts.package, ondir);
         }
 
         function ondir(err, n, pkg) {
@@ -287,6 +295,10 @@ module.exports = function resolve(x, options, callback) {
         }
     }
     function loadNodeModules(x, start, cb) {
-        processDirs(cb, nodeModulesPaths(start, opts, x));
+        var thunk = function () { return getPackageCandidates(x, start, opts); };
+        processDirs(
+            cb,
+            packageIterator ? packageIterator(x, start, thunk, opts) : thunk()
+        );
     }
 };
diff --git a/lib/sync.js b/lib/sync.js
index 79633997..cc0ec56c 100644
--- a/lib/sync.js
+++ b/lib/sync.js
@@ -38,6 +38,14 @@ var maybeUnwrapSymlink = function maybeUnwrapSymlink(x, opts) {
     return x;
 };
 
+var getPackageCandidates = function getPackageCandidates(x, start, opts) {
+    var dirs = nodeModulesPaths(start, opts, x);
+    for (var i = 0; i < dirs.length; i++) {
+        dirs[i] = path.join(dirs[i], x);
+    }
+    return dirs;
+};
+
 module.exports = function (x, options) {
     if (typeof x !== 'string') {
         throw new TypeError('Path must be a string.');
@@ -47,6 +55,7 @@ module.exports = function (x, options) {
     var isFile = opts.isFile || defaultIsFile;
     var isDirectory = opts.isDirectory || defaultIsDir;
     var readFileSync = opts.readFileSync || fs.readFileSync;
+    var packageIterator = opts.packageIterator;
 
     var extensions = opts.extensions || ['.js'];
     var basedir = opts.basedir || path.dirname(caller());
@@ -162,13 +171,15 @@ module.exports = function (x, options) {
     }
 
     function loadNodeModulesSync(x, start) {
-        var dirs = nodeModulesPaths(start, opts, x);
+        var thunk = function () { return getPackageCandidates(x, start, opts); };
+        var dirs = packageIterator ? packageIterator(x, start, thunk, opts) : thunk();
+
         for (var i = 0; i < dirs.length; i++) {
             var dir = dirs[i];
-            if (isDirectory(dir)) {
-                var m = loadAsFileSync(path.join(dir, '/', x));
+            if (isDirectory(path.dirname(dir))) {
+                var m = loadAsFileSync(dir);
                 if (m) return m;
-                var n = loadAsDirectorySync(path.join(dir, '/', x));
+                var n = loadAsDirectorySync(dir);
                 if (n) return n;
             }
         }
diff --git a/readme.markdown b/readme.markdown
index 64778cc9..cdea6778 100644
--- a/readme.markdown
+++ b/readme.markdown
@@ -80,6 +80,12 @@ options are:
     * getNodeModulesDirs - a thunk (no-argument function) that returns the paths using standard `node_modules` resolution
     * opts - the resolution options
 
+* `opts.packageIterator(request, start, opts)` - return the list of candidate paths where the packages sources may be found (probably don't use this)
+    * request - the import specifier being resolved
+    * start - lookup path
+    * getPackageCandidates - a thunk (no-argument function) that returns the paths using standard `node_modules` resolution
+    * opts - the resolution options
+
 * opts.moduleDirectory - directory (or directories) in which to recursively look for modules. default: `"node_modules"`
 
 * opts.preserveSymlinks - if true, doesn't resolve `basedir` to real path before resolving.
@@ -146,6 +152,18 @@ options are:
 
 * opts.paths - require.paths array to use if nothing is found on the normal `node_modules` recursive walk (probably don't use this)
 
+  For advanced users, `paths` can also be a `opts.paths(request, start, opts)` function
+    * request - the import specifier being resolved
+    * start - lookup path
+    * getNodeModulesDirs - a thunk (no-argument function) that returns the paths using standard `node_modules` resolution
+    * opts - the resolution options
+
+* `opts.packageIterator(request, start, opts)` - return the list of candidate paths where the packages sources may be found (probably don't use this)
+    * request - the import specifier being resolved
+    * start - lookup path
+    * getPackageCandidates - a thunk (no-argument function) that returns the paths using standard `node_modules` resolution
+    * opts - the resolution options
+
 * opts.moduleDirectory - directory (or directories) in which to recursively look for modules. default: `"node_modules"`
 
 * opts.preserveSymlinks - if true, doesn't resolve `basedir` to real path before resolving.
diff --git a/test/resolver.js b/test/resolver.js
index 521eacc0..5df8e1d0 100644
--- a/test/resolver.js
+++ b/test/resolver.js
@@ -256,6 +256,22 @@ test('other path', function (t) {
     });
 });
 
+test('path iterator', function (t) {
+    t.plan(2);
+
+    var resolverDir = path.join(__dirname, 'resolver');
+
+    var exactIterator = function (x, start, getPackageCandidates, opts) {
+        return [path.join(resolverDir, x)];
+    };
+
+    resolve('baz', { packageIterator: exactIterator }, function (err, res, pkg) {
+        if (err) t.fail(err);
+        t.equal(res, path.join(resolverDir, 'baz/quux.js'));
+        t.equal(pkg && pkg.name, 'baz');
+    });
+});
+
 test('incorrect main', function (t) {
     t.plan(1);
 
diff --git a/test/resolver/baz/package.json b/test/resolver/baz/package.json
index c41e4dbf..2f77720b 100644
--- a/test/resolver/baz/package.json
+++ b/test/resolver/baz/package.json
@@ -1,3 +1,4 @@
 {
+    "name": "baz",
     "main": "quux.js"
 }
diff --git a/test/resolver_sync.js b/test/resolver_sync.js
index 65ea5dce..aa8e2568 100644
--- a/test/resolver_sync.js
+++ b/test/resolver_sync.js
@@ -172,6 +172,21 @@ test('other path', function (t) {
     t.end();
 });
 
+test('path iterator', function (t) {
+    var resolverDir = path.join(__dirname, 'resolver');
+
+    var exactIterator = function (x, start, getPackageCandidates, opts) {
+        return [path.join(resolverDir, x)];
+    };
+
+    t.equal(
+        resolve.sync('baz', { packageIterator: exactIterator }),
+        path.join(resolverDir, 'baz/quux.js')
+    );
+
+    t.end();
+});
+
 test('incorrect main', function (t) {
     var resolverDir = path.join(__dirname, 'resolver');
     var dir = path.join(resolverDir, 'incorrect_main');