diff --git a/include/boost/fiber/detail/spinlock.hpp b/include/boost/fiber/detail/spinlock.hpp
index 6e020010..97f26d1d 100644
--- a/include/boost/fiber/detail/spinlock.hpp
+++ b/include/boost/fiber/detail/spinlock.hpp
@@ -25,33 +25,28 @@ private:
         unlocked
     };
 
-    std::atomic< atomic_spinlock_status >  state_;
+    std::atomic< atomic_spinlock_status >  state_{ atomic_spinlock_status::unlocked };
 
 public:
-    atomic_spinlock() noexcept;
+    constexpr atomic_spinlock() noexcept = default;
 
     atomic_spinlock( atomic_spinlock const&) = delete;
     atomic_spinlock & operator=( atomic_spinlock const&) = delete;
 
-    void lock();
-
+    void lock() noexcept;
     void unlock() noexcept;
 };
 
 struct non_spinlock {
-    non_spinlock() noexcept {}
-
-    void lock() {}
-
+    constexpr non_spinlock() noexcept {}
+    void lock() noexcept {}
     void unlock() noexcept {}
 };
 
 struct non_lock {
-    non_lock( non_spinlock) {}
-
-    void lock() {}
-
-    void unlock() {}
+    constexpr non_lock( non_spinlock) noexcept {}
+    void lock() noexcept {}
+    void unlock() noexcept {}
 };
 
 #if ! defined(BOOST_FIBES_NO_ATOMICS) 
diff --git a/src/detail/spinlock.cpp b/src/detail/spinlock.cpp
index 7b94b03b..7a4ae20d 100644
--- a/src/detail/spinlock.cpp
+++ b/src/detail/spinlock.cpp
@@ -16,12 +16,8 @@ namespace boost {
 namespace fibers {
 namespace detail {
 
-atomic_spinlock::atomic_spinlock() noexcept :
-    state_( atomic_spinlock_status::unlocked) {
-}
-
 void
-atomic_spinlock::lock() {
+atomic_spinlock::lock() noexcept {
     do {
         // access to CPU's cache
         // first access to state_ -> cache miss