diff --git a/src/applications/people/storage/user/PhabricatorUser.php b/src/applications/people/storage/user/PhabricatorUser.php
index eae33c1ccf..ab5a3f9e7a 100644
--- a/src/applications/people/storage/user/PhabricatorUser.php
+++ b/src/applications/people/storage/user/PhabricatorUser.php
@@ -68,26 +68,12 @@ class PhabricatorUser extends PhabricatorUserDAO {
   }
 
   private function generateConduitCertificate() {
-    $entropy = $this->generateEntropy($bytes = 256);
+    $entropy = Filesystem::readRandomBytes(256);
     $entropy = base64_encode($entropy);
     $entropy = substr($entropy, 0, 255);
     return $entropy;
   }
 
-  private function generateEntropy($bytes) {
-    $urandom = fopen('/dev/urandom', 'r');
-    if (!$urandom) {
-      throw new Exception("Failed to open /dev/urandom!");
-    }
-
-    $entropy = fread($urandom, $bytes);
-    if (strlen($entropy) != $bytes) {
-      throw new Exception("Failed to read /dev/urandom!");
-    }
-
-    return $entropy;
-  }
-
   public function comparePassword($password) {
     $password = $this->hashPassword($password);
     return ($password === $this->getPasswordHash());
@@ -137,7 +123,7 @@ class PhabricatorUser extends PhabricatorUserDAO {
   public function establishSession($session_type) {
     $conn_w = $this->establishConnection('w');
 
-    $entropy = $this->generateEntropy($bytes = 20);
+    $entropy = Filesystem::readRandomBytes(20);
 
     $session_key = sha1($entropy);
     queryfx(
diff --git a/src/applications/people/storage/user/__init__.php b/src/applications/people/storage/user/__init__.php
index 09bebc3ee3..3be82cddf2 100644
--- a/src/applications/people/storage/user/__init__.php
+++ b/src/applications/people/storage/user/__init__.php
@@ -11,6 +11,7 @@ phutil_require_module('phabricator', 'applications/phid/storage/phid');
 phutil_require_module('phabricator', 'infrastructure/env');
 phutil_require_module('phabricator', 'storage/queryfx');
 
+phutil_require_module('phutil', 'filesystem');
 phutil_require_module('phutil', 'utils');
 
 
diff --git a/src/applications/phid/storage/phid/PhabricatorPHID.php b/src/applications/phid/storage/phid/PhabricatorPHID.php
index 6289311f6a..08053a0d1c 100644
--- a/src/applications/phid/storage/phid/PhabricatorPHID.php
+++ b/src/applications/phid/storage/phid/PhabricatorPHID.php
@@ -31,14 +31,7 @@ class PhabricatorPHID extends PhabricatorPHIDDAO {
       throw new Exception("Can not generate PHID with no type.");
     }
 
-    $urandom = @fopen('/dev/urandom', 'r');
-    if (!$urandom) {
-      throw new Exception("Failed to open /dev/urandom!");
-    }
-    $entropy = fread($urandom, 20);
-    if (strlen($entropy) != 20) {
-      throw new Exception("Failed to read from /dev/urandom!");
-    }
+    $entropy = Filesystem::readRandomBytes(20);
 
     $uniq = sha1($entropy);
     $uniq = substr($uniq, 0, 20);
diff --git a/src/applications/phid/storage/phid/__init__.php b/src/applications/phid/storage/phid/__init__.php
index 5ff7852286..11b016fe93 100644
--- a/src/applications/phid/storage/phid/__init__.php
+++ b/src/applications/phid/storage/phid/__init__.php
@@ -8,6 +8,7 @@
 
 phutil_require_module('phabricator', 'applications/phid/storage/base');
 
+phutil_require_module('phutil', 'filesystem');
 phutil_require_module('phutil', 'utils');