diff --git a/ostd/condition.hh b/ostd/condition.hh
new file mode 100644
index 0000000..1f338b5
--- /dev/null
+++ b/ostd/condition.hh
@@ -0,0 +1,11 @@
+/* Condition variables.
+ *
+ * This file is part of OctaSTD. See COPYING.md for futher information.
+ */
+
+#ifndef OSTD_CONDITION_HH
+#define OSTD_CONDITION_HH
+
+#include "ostd/internal/mutex.hh"
+
+#endif
\ No newline at end of file
diff --git a/ostd/internal/mutex.hh b/ostd/internal/mutex.hh
new file mode 100644
index 0000000..229e910
--- /dev/null
+++ b/ostd/internal/mutex.hh
@@ -0,0 +1,201 @@
+/* Locking related core internals.
+ *
+ * This file is part of OctaSTD. See COPYING.md for futher information.
+ */
+
+#ifndef OSTD_INTERNAL_MUTEX_HH
+#define OSTD_INTERNAL_MUTEX_HH
+
+#include <stdlib.h>
+#include <threads.h>
+
+#include "ostd/utility.hh"
+
+namespace ostd {
+
+struct Mutex {
+    using NativeHandle = mtx_t *;
+
+    Mutex() {
+        if (mtx_init(&p_mtx, mtx_plain) != thrd_success)
+            p_mtx = 0;
+    }
+
+    ~Mutex() {
+        if (p_mtx)
+            mtx_destroy(&p_mtx);
+    }
+
+    Mutex(const Mutex &) = delete;
+    Mutex &operator=(const Mutex &) = delete;
+
+    bool lock() {
+        if (!p_mtx)
+            return false;
+        return mtx_lock(&p_mtx) == thrd_success;
+    }
+
+    int try_lock() {
+        if (!p_mtx)
+            return 0;
+        int ret = mtx_trylock(&p_mtx);
+        if (ret == thrd_busy)
+            return -1;
+        return 1;
+    }
+
+    bool unlock() {
+        if (!p_mtx)
+            return false;
+        return mtx_unlock(&p_mtx) == thrd_success;
+    }
+
+    NativeHandle native_handle() { return &p_mtx; }
+
+private:
+    mtx_t p_mtx;
+};
+
+struct DeferLock {};
+struct TryToLock {};
+struct AdoptLock {};
+
+constexpr DeferLock defer_lock {};
+constexpr TryToLock try_to_lock {};
+constexpr AdoptLock adopt_lock {};
+
+template<typename T>
+struct LockGuard {
+    using MutexType = T;
+
+    explicit LockGuard(MutexType &m): p_mtx(m) { m.lock(); }
+    LockGuard(MutexType &m, AdoptLock): p_mtx(m) {}
+    ~LockGuard() { p_mtx.unlock(); }
+
+    LockGuard(const LockGuard &) = delete;
+    LockGuard &operator=(const LockGuard &) = delete;
+
+private:
+    MutexType &p_mtx;
+};
+
+template<typename T>
+struct UniqueLock {
+    using MutexType = T;
+
+    UniqueLock(): p_mtx(nullptr), p_owns(false) {}
+
+    explicit UniqueLock(MutexType &m): p_mtx(&m), p_owns(true) {
+        m->lock();
+    }
+
+    UniqueLock(MutexType &m, DeferLock): p_mtx(&m), p_owns(false) {}
+
+    UniqueLock(MutexType &m, TryToLock): p_mtx(&m) {
+        int ret = m.try_lock();
+        if (!ret) {
+            p_mtx = nullptr;
+            p_owns = false;
+            return;
+        }
+        p_owns = (ret == 1);
+    }
+
+    UniqueLock(MutexType &m, AdoptLock): p_mtx(&m), p_owns(true) {}
+
+    ~UniqueLock() {
+        if (p_owns) p_mtx->unlock();
+    }
+
+    UniqueLock(const UniqueLock &) = delete;
+    UniqueLock &operator=(const UniqueLock &) = delete;
+
+    UniqueLock(UniqueLock &&u): p_mtx(u.p_mtx), p_owns(u.p_owns) {
+        u.p_mtx = nullptr;
+        u.p_owns = false;
+    }
+
+    UniqueLock &operator=(UniqueLock &&u) {
+        if (p_owns) p_mtx->unlock();
+        p_mtx = u.p_mtx;
+        p_owns = u.p_owns;
+        u.p_mtx = nullptr;
+        u.p_owns = false;
+        return *this;
+    }
+
+    bool lock() {
+        if (!p_mtx || p_owns) return false;
+        bool ret = p_mtx->lock();
+        if (ret) p_owns = true;
+        return ret;
+    }
+
+    int try_lock() {
+        if (!p_mtx || p_owns) return 0;
+        int ret = p_mtx->try_lock();
+        if (!ret) return 0;
+        p_owns = (ret == 1);
+        return ret;
+    }
+
+    void swap(UniqueLock &u) {
+        detail::swap_adl(p_mtx, u.p_mtx);
+        detail::swap_adl(p_owns, u.p_owns);
+    }
+
+    MutexType *release() {
+        MutexType *ret = p_mtx;
+        p_mtx = nullptr;
+        p_owns = false;
+        return ret;
+    }
+
+    bool owns_lock() const { return p_owns; }
+    explicit operator bool() const { return p_owns; }
+    MutexType *mutex() const { return p_mtx; }
+
+private:
+    MutexType *p_mtx;
+    bool p_owns;
+};
+
+struct Condition {
+    using NativeHandle = cnd_t *;
+
+    Condition() {
+        if (cnd_init(&p_cnd) != thrd_success)
+            p_cnd = 0;
+    }
+
+    Condition(const Condition &) = delete;
+    Condition &operator=(const Condition &) = delete;
+
+    ~Condition() {
+        if (p_cnd) cnd_destroy(&p_cnd);
+    }
+
+    bool signal() {
+        if (!p_cnd) return false;
+        return cnd_signal(&p_cnd) == thrd_success;
+    }
+
+    bool broadcast() {
+        if (!p_cnd) return false;
+        return cnd_broadcast(&p_cnd) == thrd_success;
+    }
+
+    bool wait(UniqueLock<Mutex> &l) {
+        if (!p_cnd) return false;
+        return cnd_wait(&p_cnd, l.mutex()->native_handle()) == thrd_success;
+    }
+
+    NativeHandle native_handle() { return &p_cnd; }
+
+private:
+    cnd_t p_cnd;
+};
+
+} /* namespace ostd */
+
+#endif
\ No newline at end of file
diff --git a/ostd/mutex.hh b/ostd/mutex.hh
new file mode 100644
index 0000000..fbd698e
--- /dev/null
+++ b/ostd/mutex.hh
@@ -0,0 +1,11 @@
+/* Locking primitives.
+ *
+ * This file is part of OctaSTD. See COPYING.md for futher information.
+ */
+
+#ifndef OSTD_MUTEX_HH
+#define OSTD_MUTEX_HH
+
+#include "ostd/internal/mutex.hh"
+
+#endif
\ No newline at end of file
diff --git a/ostd/thread.hh b/ostd/thread.hh
index ca62441..ed73a69 100644
--- a/ostd/thread.hh
+++ b/ostd/thread.hh
@@ -125,10 +125,10 @@ struct Thread {
             abort();
     }
 
-    operator bool() const { return joinable(); }
+    explicit operator bool() const { return joinable(); }
     bool joinable() const { return p_thread != 0; }
 
-    NativeHandle native_handle() const { return p_thread; }
+    NativeHandle native_handle() { return p_thread; }
 
     detail::ThreadId get_id() {
         return p_thread;