diff --git a/src/kernlib/display.cpp b/src/kernlib/display.cpp
index 26304d0..039522a 100644
--- a/src/kernlib/display.cpp
+++ b/src/kernlib/display.cpp
@@ -42,16 +42,12 @@ class ConsoleDisplay: public Display {
     clean();
   }
   void write(const char *str) {
-    uint64_t t = EnterCritical();
-    mutex.lock();
+    Mutex::CriticalLock lock(mutex);
     while (*str != 0) putc(*(str++));
-    mutex.release();
-    LeaveCritical(t);
   }
   void clean() {
-    mutex.lock();
+    Mutex::Lock lock(mutex);
     Memory::fill(base, 0, size);
-    mutex.release();
   }
 };
 
@@ -132,16 +128,12 @@ class FramebufferDisplay: public Display {
     clean();
   }
   void write(const char *str) {
-    uint64_t t = EnterCritical();
-    mutex.lock();
+    Mutex::CriticalLock lock(mutex);
     while (*str != 0) putc(*(str++));
-    mutex.release();
-    LeaveCritical(t);
   }
   void clean() {
-    mutex.lock();
+    Mutex::Lock lock(mutex);
     Memory::zero(framebuffer, bufferSize());
-    mutex.release();
   }
 };
 
@@ -164,12 +156,9 @@ class SerialDisplay: public Display {
     Port<port + 3>::out<uint8_t>(0x03);
   }
   void write(const char *str) {
-    uint64_t t = EnterCritical();
-    mutex.lock();
+    Mutex::CriticalLock lock(mutex);
     char c;
     while ((c = *str++) != 0) Port<port>::out(uint8_t(c));
-    mutex.release();
-    LeaveCritical(t);
   }
   void clean() {}
 };
@@ -221,11 +210,8 @@ void Display::setup() {
 
 Display *Display::getInstance() {
   if (instance) return instance;
-  uint64_t t = EnterCritical();
-  instanceMutex.lock();
+  Mutex::CriticalLock lock(instanceMutex);
   if (!instance) setup();
-  instanceMutex.release();
-  LeaveCritical(t);
   return instance;
 }
 
diff --git a/src/kernlib/include/kernlib.hpp b/src/kernlib/include/kernlib.hpp
index c76cb43..8bd7618 100644
--- a/src/kernlib/include/kernlib.hpp
+++ b/src/kernlib/include/kernlib.hpp
@@ -3,7 +3,6 @@
 
 #pragma once
 
-#include "kernlib/cpu.hpp"
 #include "kernlib/display.hpp"
 #include "kernlib/mem.hpp"
 #include "kernlib/mutex.hpp"
diff --git a/src/kernlib/include/kernlib/cpu.hpp b/src/kernlib/include/kernlib/cpu.hpp
deleted file mode 100644
index d1d7efc..0000000
--- a/src/kernlib/include/kernlib/cpu.hpp
+++ /dev/null
@@ -1,23 +0,0 @@
-//    PhoeniX OS Kernel library cpu functions
-//    Copyright © 2017 Yury Popov a.k.a. PhoeniX
-
-#pragma once
-#include "std.hpp"
-
-namespace klib {
-  inline static uint64_t rdtsc() {
-    uint32_t eax, edx;
-    asm volatile("rdtsc":"=a"(eax), "=d"(edx));
-    return ((uint64_t(edx) << 32) | eax);
-  }
-}  // namespace klib
-
-inline static uint64_t __attribute__((always_inline)) EnterCritical() {
-  uint64_t flags;
-  asm volatile("pushfq; cli; pop %q0":"=r"(flags));
-  return flags;
-}
-
-inline static void LeaveCritical(uint64_t flags) {
-  asm volatile("push %q0; popfq"::"r"(flags));
-}
diff --git a/src/kernlib/include/kernlib/mutex.hpp b/src/kernlib/include/kernlib/mutex.hpp
index 5d5bb4c..f8e2cd4 100644
--- a/src/kernlib/include/kernlib/mutex.hpp
+++ b/src/kernlib/include/kernlib/mutex.hpp
@@ -4,9 +4,29 @@
 #pragma once
 #include "std.hpp"
 
+class CriticalSection {
+ private:
+  uint64_t flags;
+
+ public:
+  inline static uint64_t __attribute__((always_inline)) enter() {
+    uint64_t flags;
+    asm volatile("pushfq; cli; pop %q0":"=r"(flags));
+    return flags;
+  }
+
+  inline static void leave(uint64_t flags) {
+    asm volatile("push %q0; popfq"::"r"(flags));
+  }
+
+  CriticalSection() : flags(enter()) {}
+  ~CriticalSection() { leave(flags); }
+};
+
 class Mutex {
  private:
   bool state;
+
  public:
   Mutex(): state(0) {}
   inline void lock() {
@@ -28,4 +48,20 @@ class Mutex {
   inline void release() {
     asm volatile("movw $0, %0"::"m"(state));
   }
+  class Lock {
+   private:
+    Mutex *mutex;
+   public:
+    explicit Lock(Mutex *mutex) : mutex(mutex) { mutex->lock(); }
+    explicit Lock(Mutex &mutex) : Lock(&mutex) {}
+    ~Lock() { mutex->release(); }
+  };
+  class CriticalLock: public CriticalSection {
+   private:
+    Mutex *mutex;
+   public:
+    explicit CriticalLock(Mutex *mutex) : mutex(mutex) { mutex->lock(); }
+    explicit CriticalLock(Mutex &mutex) : CriticalLock(&mutex) {}
+    ~CriticalLock() { mutex->release(); }
+  };
 };
diff --git a/src/kernlib/include/kernlib/std.hpp b/src/kernlib/include/kernlib/std.hpp
index 43c6bf4..338561b 100644
--- a/src/kernlib/include/kernlib/std.hpp
+++ b/src/kernlib/include/kernlib/std.hpp
@@ -25,6 +25,12 @@ namespace klib {
   int strncmp(const char*, const char*, int) PURE;
   int strcmp(const char*, const char*) PURE;
 
+  inline static uint64_t rdtsc() {
+    uint32_t eax, edx;
+    asm volatile("rdtsc":"=a"(eax), "=d"(edx));
+    return ((uint64_t(edx) << 32) | eax);
+  }
+
   inline static uintptr_t __align(uintptr_t base, size_t align) {
     if (base % align == 0)
       return base;
diff --git a/src/platform/acpi.cpp b/src/platform/acpi.cpp
index 887a1a5..ea6dbbe 100644
--- a/src/platform/acpi.cpp
+++ b/src/platform/acpi.cpp
@@ -12,12 +12,8 @@ ACPI* ACPI::controller = nullptr;
 
 ACPI* ACPI::getController() {
   if (controller) return controller;
-  uint64_t t = EnterCritical();
-  controllerMutex.lock();
-  if (!controller)
-    controller = new ACPI();
-  controllerMutex.release();
-  LeaveCritical(t);
+  Mutex::CriticalLock lock(controllerMutex);
+  if (!controller) controller = new ACPI();
   return controller;
 }
 
diff --git a/src/platform/heap.cpp b/src/platform/heap.cpp
index 58168ff..297c9fe 100644
--- a/src/platform/heap.cpp
+++ b/src/platform/heap.cpp
@@ -28,12 +28,10 @@ Mutex Heap::heap_mutex;
 void* Heap::alloc(size_t size, size_t align) {
   if (size == 0)
     return nullptr;
-  heap_mutex.lock();
+  Mutex::Lock lock(heap_mutex);
 
-  if (!heap_pages)
-    heap_pages = reinterpret_cast<HeapPage*>(Pagetable::alloc());
-  if (!allocs)
-    allocs = reinterpret_cast<AllocTable*>(Pagetable::alloc());
+  if (!heap_pages) heap_pages = reinterpret_cast<HeapPage*>(Pagetable::alloc());
+  if (!allocs) allocs = reinterpret_cast<AllocTable*>(Pagetable::alloc());
 
   uintptr_t ptr = 0, ptr_top;
 
@@ -123,7 +121,6 @@ void* Heap::alloc(size_t size, size_t align) {
     table = table->next;
   }
 done:
-  heap_mutex.release();
 
   void *a = reinterpret_cast<void*>(ptr);
   Memory::zero(a, size);
@@ -131,51 +128,47 @@ void* Heap::alloc(size_t size, size_t align) {
   return a;
 }
 void Heap::free(void* addr) {
-  if (addr == nullptr)
-    return;
-  heap_mutex.lock();
+  if (addr == nullptr) return;
+  Mutex::Lock lock(heap_mutex);
   AllocTable *t = allocs;
   while (1) {
     for (int i = 0; i < 255; i++) {
       if (t->allocs[i].addr == addr) {
         t->allocs[i].addr = nullptr;
         t->allocs[i].size = 0;
-        goto end;
+        return;
       }
     }
-    if (t->next == nullptr)
-      goto end;
+    if (t->next == nullptr) return;
     t = t->next;
   }
-  end: heap_mutex.release();
 }
 void *Heap::realloc(void *addr, size_t size, size_t align) {
   if (size == 0) {
     free(addr);
     return nullptr;
   }
-  if (addr == nullptr)
-    return alloc(size, align);
-  heap_mutex.lock();
-  AllocTable *t = allocs;
+  if (addr == nullptr) return alloc(size, align);
   size_t oldsize = 0;
-  while (t != nullptr) {
-    for (int i = 0; i < 255; i++) {
-      if (t->allocs[i].addr == addr) {
-        oldsize = t->allocs[i].size;
-        if (oldsize >= size) {
-          t->allocs[i].size = size;
-          heap_mutex.release();
-          return addr;
+  {
+    Mutex::Lock lock(heap_mutex);
+    AllocTable *t = allocs;
+    while (t != nullptr) {
+      for (int i = 0; i < 255; i++) {
+        if (t->allocs[i].addr == addr) {
+          oldsize = t->allocs[i].size;
+          if (oldsize >= size) {
+            t->allocs[i].size = size;
+            return addr;
+          }
+          break;
         }
-        break;
       }
+      if (oldsize != 0)
+        break;
+      t = t->next;
     }
-    if (oldsize != 0)
-      break;
-    t = t->next;
   }
-  heap_mutex.release();
   if (oldsize == 0)
     return nullptr;
   void *newptr = alloc(size, align);
diff --git a/src/platform/interrupts.cpp b/src/platform/interrupts.cpp
index 0dc61de..6e04ba3 100644
--- a/src/platform/interrupts.cpp
+++ b/src/platform/interrupts.cpp
@@ -223,8 +223,9 @@ void Interrupts::print(uint8_t num, CallbackRegs *regs, uint32_t code, const Pro
 
 uint64_t __attribute__((sysv_abi)) Interrupts::handle(
     unsigned char intr, uint64_t stack, uint64_t *pagetable) {
-  fault.lock();
-  fault.release();
+  {
+    Mutex::Lock lock(fault);
+  }
   uint64_t *rsp = reinterpret_cast<uint64_t*>(stack);
   bool has_code = (intr < 0x20) && FAULTS[intr].has_error_code;
   uint32_t error_code = 0;
@@ -252,10 +253,11 @@ uint64_t __attribute__((sysv_abi)) Interrupts::handle(
   size_t idx = 0;
   Callback *cb;
   for (;;) {
-    callback_locks[intr].lock();
-    cb = (callbacks[intr].getCount() > idx) ? callbacks[intr][idx] : nullptr;
-    idx++;
-    callback_locks[intr].release();
+    {
+      Mutex::Lock lock(callback_locks[intr]);
+      cb = (callbacks[intr].getCount() > idx) ? callbacks[intr][idx] : nullptr;
+      idx++;
+    }
     if (cb == nullptr) break;
     handled = cb(intr, error_code, &cb_regs);
     if (handled) break;
@@ -402,9 +404,6 @@ uint16_t Interrupts::getIRQmask() {
 }
 
 void Interrupts::addCallback(uint8_t intr, Callback* cb) {
-  uint64_t t = EnterCritical();
-  callback_locks[intr].lock();
+  Mutex::CriticalLock lock(callback_locks[intr]);
   callbacks[intr].add(cb);
-  callback_locks[intr].release();
-  LeaveCritical(t);
 }
diff --git a/src/platform/pagetable.cpp b/src/platform/pagetable.cpp
index 3baa6b7..3812f85 100644
--- a/src/platform/pagetable.cpp
+++ b/src/platform/pagetable.cpp
@@ -412,12 +412,8 @@ void* Pagetable::_map(const void* mem) {
 }
 
 void* Pagetable::map(const void* mem) {
-  uint64_t t = EnterCritical();
-  page_mutex.lock();
-  void *addr = _map(mem);
-  page_mutex.release();
-  LeaveCritical(t);
-  return addr;
+  Mutex::CriticalLock lock(page_mutex);
+  return _map(mem);
 }
 
 void* Pagetable::_alloc(uint8_t avl, bool nolow) {
@@ -441,18 +437,13 @@ void* Pagetable::_alloc(uint8_t avl, bool nolow) {
 }
 
 void* Pagetable::alloc(uint8_t avl) {
-  uint64_t t = EnterCritical();
-  page_mutex.lock();
-  void* ret = _alloc(avl);
-  page_mutex.release();
-  LeaveCritical(t);
-  return ret;
+  Mutex::CriticalLock lock(page_mutex);
+  return _alloc(avl);
 }
 
 void Pagetable::free(void* page) {
   PTE *pagetable; asm volatile("mov %%cr3, %q0":"=r"(pagetable));
-  uint64_t t = EnterCritical();
-  page_mutex.lock();
+  Mutex::CriticalLock lock(page_mutex);
   PTE *pdata = PTE::find(page, pagetable);
   if ((pdata != nullptr) && pdata->present) {
     pdata->present = 0;
@@ -460,6 +451,4 @@ void Pagetable::free(void* page) {
     if ((uintptr_t(addr) >> 12) < last_page)
       last_page = uintptr_t(addr) >> 12;
   }
-  page_mutex.release();
-  LeaveCritical(t);
 }
diff --git a/src/platform/smp.cpp b/src/platform/smp.cpp
index b23ec56..006c64e 100644
--- a/src/platform/smp.cpp
+++ b/src/platform/smp.cpp
@@ -20,8 +20,7 @@ void SMP::setup() {
   Interrupts::loadVector();
   ACPI::getController()->activateCPU();
   Syscall::setup();
-  startupMutex.lock();
-  startupMutex.release();
+  Mutex::Lock lock(startupMutex);
 }
 
 void SMP::startup() {
@@ -78,24 +77,23 @@ void SMP::init() {
   if (nullcpus > 0)
     nullcpus--;
 
-  startupMutex.lock();
-
-  for (uint32_t i = 0; i < cpuCount; i++) {
-    if (info->cpuids[i] != localId) {
-      acpi->sendCPUInit(uint32_t(info->cpuids[i]));
-    }
-  }
-  while (cpuCount - nullcpus != acpi->getActiveCPUCount()) {
+  {
+    Mutex::Lock lock(startupMutex);
     for (uint32_t i = 0; i < cpuCount; i++) {
       if (info->cpuids[i] != localId) {
-        acpi->sendCPUStartup(uint32_t(info->cpuids[i]), smp_init_vector);
+        acpi->sendCPUInit(uint32_t(info->cpuids[i]));
       }
     }
-    asm volatile("hlt");
+    while (cpuCount - nullcpus != acpi->getActiveCPUCount()) {
+      for (uint32_t i = 0; i < cpuCount; i++) {
+        if (info->cpuids[i] != localId) {
+          acpi->sendCPUStartup(uint32_t(info->cpuids[i]), smp_init_vector);
+        }
+      }
+      asm volatile("hlt");
+    }
   }
 
-  startupMutex.release();
-
   delete info->cpuids;
   delete info->stacks;
   Pagetable::free(startupCode);
diff --git a/src/process/modules.cpp b/src/process/modules.cpp
index 6d47358..16c2109 100644
--- a/src/process/modules.cpp
+++ b/src/process/modules.cpp
@@ -191,9 +191,7 @@ void ModuleManager::init() {
 
 ModuleManager* ModuleManager::getManager() {
   if (manager) return manager;
-  managerMutex.lock();
-  if (!manager)
-    manager = new ModuleManager();
-  managerMutex.release();
+  Mutex::Lock lock(managerMutex);
+  if (!manager) manager = new ModuleManager();
   return manager;
 }
diff --git a/src/process/processmanager.cpp b/src/process/processmanager.cpp
index 1601a89..e34c846 100644
--- a/src/process/processmanager.cpp
+++ b/src/process/processmanager.cpp
@@ -17,12 +17,8 @@ ProcessManager* ProcessManager::manager = nullptr;
 
 ProcessManager* ProcessManager::getManager() {
   if (manager) return manager;
-  uint64_t t = EnterCritical();
-  managerMutex.lock();
-  if (!manager)
-    manager = new ProcessManager();
-  managerMutex.release();
-  LeaveCritical(t);
+  Mutex::CriticalLock lock(managerMutex);
+  if (!manager) manager = new ProcessManager();
   return manager;
 }
 
@@ -44,17 +40,10 @@ bool ProcessManager::FaultHandler(uint8_t intr, uint32_t code, Interrupts::Callb
 bool ProcessManager::SwitchProcess(Interrupts::CallbackRegs *regs) {
   uintptr_t loopbase = uintptr_t(&process_loop), looptop;
   asm volatile("lea process_loop_top(%%rip), %q0":"=r"(looptop));
-  processSwitchMutex.lock();
-  if (regs->dpl == 0 &&
-      (regs->rip < loopbase || regs->rip >= looptop)) {
-    processSwitchMutex.release();
-    return false;
-  }
+  Mutex::Lock lock(processSwitchMutex);
+  if (regs->dpl == 0 && (regs->rip < loopbase || regs->rip >= looptop)) return false;
   QueuedThread *thread = nextThread;
-  if (thread == nullptr) {
-    processSwitchMutex.release();
-    return false;
-  }
+  if (thread == nullptr) return false;
   nextThread = thread->next;
   if (thread == lastThread)
     lastThread = nullptr;
@@ -88,46 +77,40 @@ bool ProcessManager::SwitchProcess(Interrupts::CallbackRegs *regs) {
     th->regs.r8, th->regs.r9, th->regs.r10, th->regs.r11,
     th->regs.r12, th->regs.r13, th->regs.r14, th->regs.r15
   };
-  processSwitchMutex.release();
   return true;
 }
 
 bool ProcessManager::HandleFault(uint8_t intr, uint32_t code, Interrupts::CallbackRegs *regs) {
   if (regs->dpl == 0) return false;
-  uint64_t t = EnterCritical();
-  processSwitchMutex.lock();
-  QueuedThread *thread = cpuThreads[regs->cpuid];
-  cpuThreads[regs->cpuid] = nullptr;
-  processSwitchMutex.release();
-  LeaveCritical(t);
+  QueuedThread *thread;
+  {
+    Mutex::CriticalLock lock(processSwitchMutex);
+    thread = cpuThreads[regs->cpuid];
+    cpuThreads[regs->cpuid] = nullptr;
+  }
   if (!thread) return false;
   Interrupts::print(intr, regs, code, thread->process);
   delete thread->process;
   delete thread;
-  if (SwitchProcess(regs))
-    return true;
-  t = EnterCritical();
-  processSwitchMutex.lock();
-  asm volatile("mov %%cr3, %0":"=r"(regs->cr3));
-  regs->rip = uintptr_t(&process_loop);
-  regs->cs = 0x08;
-  regs->ss = 0x10;
-  regs->dpl = 0;
-  processSwitchMutex.release();
-  LeaveCritical(t);
+  if (SwitchProcess(regs)) return true;
+  {
+    Mutex::CriticalLock lock(processSwitchMutex);
+    asm volatile("mov %%cr3, %0":"=r"(regs->cr3));
+    regs->rip = uintptr_t(&process_loop);
+    regs->cs = 0x08;
+    regs->ss = 0x10;
+    regs->dpl = 0;
+  }
   return true;
 }
 
 uint64_t ProcessManager::RegisterProcess(Process *process) {
-  uint64_t t = EnterCritical();
-  processSwitchMutex.lock();
+  Mutex::CriticalLock lock(processSwitchMutex);
   uint64_t pid = 1;
   for (size_t i = 0; i < processes.getCount(); i++) {
     pid = klib::max(pid, processes[i]->getId());
   }
   processes.add(process);
-  processSwitchMutex.release();
-  LeaveCritical(t);
   return pid;
 }
 
@@ -136,20 +119,16 @@ void ProcessManager::queueThread(Process *process, Thread *thread) {
   q->process = process;
   q->thread = thread;
   q->next = nullptr;
-  uint64_t t = EnterCritical();
-  processSwitchMutex.lock();
+  Mutex::CriticalLock lock(processSwitchMutex);
   if (lastThread) {
     lastThread = (lastThread->next = q);
   } else {
     lastThread = nextThread = q;
   }
-  processSwitchMutex.release();
-  LeaveCritical(t);
 }
 
 void ProcessManager::dequeueThread(Thread *thread) {
-  uint64_t t = EnterCritical();
-  processSwitchMutex.lock();
+  Mutex::CriticalLock lock(processSwitchMutex);
   QueuedThread *next = nextThread, *prev = nullptr;
   while (next != nullptr) {
     if (next->thread != thread) {
@@ -172,16 +151,11 @@ void ProcessManager::dequeueThread(Thread *thread) {
     delete cpuThreads[cpu];
     cpuThreads[cpu] = nullptr;
   }
-  processSwitchMutex.release();
-  LeaveCritical(t);
 }
 
 Process *ProcessManager::currentProcess() {
   uint64_t cpuid = ACPI::getController()->getCPUID();
-  uint64_t t = EnterCritical();
-  processSwitchMutex.lock();
+  Mutex::CriticalLock lock(processSwitchMutex);
   QueuedThread *curr = cpuThreads[cpuid];
-  processSwitchMutex.release();
-  LeaveCritical(t);
   return curr ? curr->process : nullptr;
 }