diff --git a/Kernel/TTY/PTYMultiplexer.cpp b/Kernel/TTY/PTYMultiplexer.cpp
index a45bc6b8205..4dce9e97645 100644
--- a/Kernel/TTY/PTYMultiplexer.cpp
+++ b/Kernel/TTY/PTYMultiplexer.cpp
@@ -24,9 +24,11 @@ PTYMultiplexer& PTYMultiplexer::the()
 UNMAP_AFTER_INIT PTYMultiplexer::PTYMultiplexer()
     : CharacterDevice(5, 2)
 {
-    m_freelist.ensure_capacity(max_pty_pairs);
-    for (int i = max_pty_pairs; i > 0; --i)
-        m_freelist.unchecked_append(i - 1);
+    m_freelist.with_exclusive([&](auto& freelist) {
+        freelist.ensure_capacity(max_pty_pairs);
+        for (int i = max_pty_pairs; i > 0; --i)
+            freelist.unchecked_append(i - 1);
+    });
 }
 
 UNMAP_AFTER_INIT PTYMultiplexer::~PTYMultiplexer()
@@ -35,27 +37,30 @@ UNMAP_AFTER_INIT PTYMultiplexer::~PTYMultiplexer()
 
 KResultOr<NonnullRefPtr<FileDescription>> PTYMultiplexer::open(int options)
 {
-    MutexLocker locker(m_lock);
-    if (m_freelist.is_empty())
-        return EBUSY;
-    auto master_index = m_freelist.take_last();
-    auto master = MasterPTY::try_create(master_index);
-    if (!master)
-        return ENOMEM;
-    dbgln_if(PTMX_DEBUG, "PTYMultiplexer::open: Vending master {}", master->index());
-    auto description = FileDescription::create(*master);
-    if (!description.is_error()) {
-        description.value()->set_rw_mode(options);
-        description.value()->set_file_flags(options);
-    }
-    return description;
+    return m_freelist.with_exclusive([&](auto& freelist) -> KResultOr<NonnullRefPtr<FileDescription>> {
+        if (freelist.is_empty())
+            return EBUSY;
+
+        auto master_index = freelist.take_last();
+        auto master = MasterPTY::try_create(master_index);
+        if (!master)
+            return ENOMEM;
+        dbgln_if(PTMX_DEBUG, "PTYMultiplexer::open: Vending master {}", master->index());
+        auto description = FileDescription::create(*master);
+        if (!description.is_error()) {
+            description.value()->set_rw_mode(options);
+            description.value()->set_file_flags(options);
+        }
+        return description;
+    });
 }
 
 void PTYMultiplexer::notify_master_destroyed(Badge<MasterPTY>, unsigned index)
 {
-    MutexLocker locker(m_lock);
-    m_freelist.append(index);
-    dbgln_if(PTMX_DEBUG, "PTYMultiplexer: {} added to freelist", index);
+    m_freelist.with_exclusive([&](auto& freelist) {
+        freelist.append(index);
+        dbgln_if(PTMX_DEBUG, "PTYMultiplexer: {} added to freelist", index);
+    });
 }
 
 }
diff --git a/Kernel/TTY/PTYMultiplexer.h b/Kernel/TTY/PTYMultiplexer.h
index 5f1ee38e3e1..4c7f4892420 100644
--- a/Kernel/TTY/PTYMultiplexer.h
+++ b/Kernel/TTY/PTYMultiplexer.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2018-2021, Andreas Kling <kling@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
@@ -43,10 +43,8 @@ private:
     // ^CharacterDevice
     virtual StringView class_name() const override { return "PTYMultiplexer"; }
 
-    Mutex m_lock { "PTYMultiplexer" };
-
     static constexpr size_t max_pty_pairs = 64;
-    Vector<unsigned, max_pty_pairs> m_freelist;
+    ProtectedValue<Vector<unsigned, max_pty_pairs>> m_freelist;
 };
 
 }