diff --git a/prelude/bootstrap.js b/prelude/bootstrap.js
index f6c5f190e..af4f6579a 100644
--- a/prelude/bootstrap.js
+++ b/prelude/bootstrap.js
@@ -93,6 +93,10 @@ EXECSTAT.birthtimeMs = EXECSTAT.birthtime.getTime();
 
 var mountpoints = [];
 
+function isRegExp(val) {
+  return require('util').types.isRegExp(val);
+}
+
 function insideMountpoint(f) {
   if (!insideSnapshot(f)) return null;
   var file = normalizePath(f);
@@ -100,6 +104,8 @@ function insideMountpoint(f) {
     .map((mountpoint) => {
       var { interior } = mountpoint;
       var { exterior } = mountpoint;
+      if (isRegExp(interior) && interior.test(file))
+        return file.replace(interior, exterior);
       if (interior === file) return exterior;
       var left = interior + require('path').sep;
       if (file.slice(0, left.length) !== left) return null;
@@ -113,9 +119,14 @@ function insideMountpoint(f) {
 
 function readdirMountpoints(path) {
   return mountpoints
-    .map((mountpoint) => mountpoint.interior)
-    .filter((interior) => require('path').dirname(interior) === path)
-    .map((interior) => require('path').basename(interior));
+    .filter(({ interior }) => {
+      if (isRegExp(interior)) return interior.test(path);
+      return require('path').dirname(interior) === path;
+    })
+    .map(({ interior, exterior }) => {
+      if (isRegExp(interior)) return path.replace(interior, exterior);
+      return require('path').basename(interior);
+    });
 }
 
 function translate(f) {
diff --git a/test/test-1121-regexp-mountpoints/main.js b/test/test-1121-regexp-mountpoints/main.js
new file mode 100644
index 000000000..db0907f52
--- /dev/null
+++ b/test/test-1121-regexp-mountpoints/main.js
@@ -0,0 +1,34 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+const assert = require('assert');
+const utils = require('../utils.js');
+
+assert(!module.parent);
+assert(__dirname === process.cwd());
+
+const target = process.argv[2] || 'host';
+const input = './test-x-index.js';
+const output = './run-time/test-output.exe';
+
+let right;
+utils.mkdirp.sync(path.dirname(output));
+utils.mkdirp.sync(path.join(path.dirname(output), 'plugins-D-ext'));
+
+fs.writeFileSync(
+  path.join(path.dirname(output), 'plugins-D-ext/test-y-require-D.js'),
+  fs.readFileSync('./plugins-D-ext/test-y-require-D.js')
+);
+
+utils.pkg.sync(['--target', target, '--output', output, input]);
+
+right = utils.spawn.sync('./' + path.basename(output), [], {
+  cwd: path.dirname(output),
+});
+
+assert.strictEqual(right, 'I am D\ntest-x-index.js\n');
+
+utils.vacuum.sync(path.dirname(output));
diff --git a/test/test-1121-regexp-mountpoints/plugins-D-ext/test-y-require-D.js b/test/test-1121-regexp-mountpoints/plugins-D-ext/test-y-require-D.js
new file mode 100644
index 000000000..57f2e7f42
--- /dev/null
+++ b/test/test-1121-regexp-mountpoints/plugins-D-ext/test-y-require-D.js
@@ -0,0 +1,10 @@
+'use strict';
+
+var assert = require('assert');
+
+if (__dirname.indexOf('snapshot') < 0) {
+  console.log(__dirname);
+  assert(false);
+}
+
+console.log('I am D');
diff --git a/test/test-1121-regexp-mountpoints/test-x-index.js b/test/test-1121-regexp-mountpoints/test-x-index.js
new file mode 100644
index 000000000..dd33481fc
--- /dev/null
+++ b/test/test-1121-regexp-mountpoints/test-x-index.js
@@ -0,0 +1,17 @@
+'use strict';
+
+var fs = require('fs');
+var path = require('path');
+
+var myDirectory = path.dirname(process.execPath);
+
+process.pkg.mount(
+  /^(.*)regexp_mountpoint_test(.*)$/,
+  function (match, group1, group2) {
+    return path.join(myDirectory, 'plugins-D-ext', group2);
+  }
+);
+
+require('./regexp_mountpoint_test/test-y-require-D.js'.slice());
+
+console.log(fs.readdirSync(__dirname).join('\n'));