diff --git a/lib/src/dbus_auth_client.dart b/lib/src/dbus_auth_client.dart
index a6c3f06..75f6ed1 100644
--- a/lib/src/dbus_auth_client.dart
+++ b/lib/src/dbus_auth_client.dart
@@ -1,9 +1,10 @@
 import 'dart:async';
 import 'dart:io';
 
+import 'package:posix/posix.dart';
+
 import 'dbus_uuid.dart';
-import 'getsid.dart';
-import 'getuid.dart';
+import 'getsid.dart' as getsid;
 
 /// A client for D-Bus authentication.
 class DBusAuthClient {
@@ -129,7 +130,7 @@ class DBusAuthClient {
     if (Platform.isLinux) {
       authId = getuid().toString();
     } else if (Platform.isWindows) {
-      authId = getsid();
+      authId = getsid.getsid();
     } else {
       throw 'Authentication not supported on ${Platform.operatingSystem}';
     }
diff --git a/lib/src/dbus_client.dart b/lib/src/dbus_client.dart
index fe3ca35..4092699 100644
--- a/lib/src/dbus_client.dart
+++ b/lib/src/dbus_client.dart
@@ -2,6 +2,8 @@ import 'dart:async';
 import 'dart:convert';
 import 'dart:io';
 
+import 'package:posix/posix.dart';
+
 import 'dbus_address.dart';
 import 'dbus_auth_client.dart';
 import 'dbus_bus_name.dart';
@@ -22,7 +24,6 @@ import 'dbus_read_buffer.dart';
 import 'dbus_signal.dart';
 import 'dbus_value.dart';
 import 'dbus_write_buffer.dart';
-import 'getuid.dart';
 
 /// Reply received when calling [DBusClient.requestName].
 enum DBusRequestNameReply { primaryOwner, inQueue, exists, alreadyOwner }
diff --git a/lib/src/dbus_server.dart b/lib/src/dbus_server.dart
index db3ce6b..77e8d91 100644
--- a/lib/src/dbus_server.dart
+++ b/lib/src/dbus_server.dart
@@ -3,6 +3,8 @@ import 'dart:convert';
 import 'dart:io';
 import 'dart:math';
 
+import 'package:posix/posix.dart';
+
 import 'dbus_address.dart';
 import 'dbus_auth_server.dart';
 import 'dbus_bus_name.dart';
@@ -20,7 +22,6 @@ import 'dbus_read_buffer.dart';
 import 'dbus_uuid.dart';
 import 'dbus_value.dart';
 import 'dbus_write_buffer.dart';
-import 'getuid.dart';
 
 /// Results of starting a service.
 enum DBusServerStartServiceResult { success, alreadyRunning, notFound }
diff --git a/lib/src/getuid.dart b/lib/src/getuid.dart
deleted file mode 100644
index 6911ed4..0000000
--- a/lib/src/getuid.dart
+++ /dev/null
@@ -1,2 +0,0 @@
-// Conditionally import the FFI version, so this doesn't break web builds.
-export 'getuid_stub.dart' if (dart.library.ffi) 'getuid_linux.dart';
diff --git a/lib/src/getuid_linux.dart b/lib/src/getuid_linux.dart
deleted file mode 100644
index de6a516..0000000
--- a/lib/src/getuid_linux.dart
+++ /dev/null
@@ -1,16 +0,0 @@
-import 'dart:ffi';
-import 'dart:io';
-
-typedef _GetuidC = Int32 Function();
-typedef _GetuidDart = int Function();
-
-/// Gets the user ID of the current user.
-int getuid() {
-  if (!Platform.isLinux) {
-    throw 'Unable to determine UID on this system';
-  }
-
-  final dylib = DynamicLibrary.open('libc.so.6');
-  final getuidP = dylib.lookupFunction<_GetuidC, _GetuidDart>('getuid');
-  return getuidP();
-}
diff --git a/lib/src/getuid_stub.dart b/lib/src/getuid_stub.dart
deleted file mode 100644
index ebfe08b..0000000
--- a/lib/src/getuid_stub.dart
+++ /dev/null
@@ -1,4 +0,0 @@
-/// Gets the user ID of the current user.
-int getuid() {
-  throw 'Unable to determine UID on this system';
-}
diff --git a/pubspec.yaml b/pubspec.yaml
index 48c9a82..2d29bdf 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -18,6 +18,7 @@ dependencies:
   args: ^2.0.0
   ffi: ^2.0.0
   meta: ^1.3.0
+  posix: ^5.0.0
   xml: ^6.1.0
 
 dev_dependencies:
diff --git a/test/dbus_test.dart b/test/dbus_test.dart
index 6079e2e..84078be 100644
--- a/test/dbus_test.dart
+++ b/test/dbus_test.dart
@@ -9,7 +9,7 @@ import 'package:dbus/src/dbus_match_rule.dart';
 import 'package:dbus/src/dbus_member_name.dart';
 import 'package:dbus/src/dbus_message.dart';
 import 'package:dbus/src/dbus_uuid.dart';
-import 'package:dbus/src/getuid.dart';
+import 'package:posix/posix.dart';
 import 'package:test/test.dart';
 
 // Test server that exposes an activatable service.