diff -rupN a/doomsday/libdeng2/include/de/data/lockable.h b/doomsday/libdeng2/include/de/data/lockable.h
--- a/doomsday/libdeng2/include/de/data/lockable.h	2012-12-28 01:04:26.509229424 -0600
+++ b/doomsday/libdeng2/include/de/data/lockable.h	2012-12-31 23:20:56.350330827 -0600
@@ -56,9 +56,8 @@ public:
 
 private:
     /// Pointer to the internal mutex data.
-    mutable QMutex _mutex;
-
-    mutable int _lockCount;
+    struct Instance;
+    Instance *d;
 };
 
 } // namespace de
diff -rupN a/doomsday/libdeng2/src/data/lockable.cpp b/doomsday/libdeng2/src/data/lockable.cpp
--- a/doomsday/libdeng2/src/data/lockable.cpp	2012-12-28 01:04:26.500229536 -0600
+++ b/doomsday/libdeng2/src/data/lockable.cpp	2012-12-31 23:24:37.037571856 -0600
@@ -20,50 +20,69 @@
 #include "de/Lockable"
 #include "de/error.h"
 
-using namespace de;
+namespace de {
 
-#define LOCK_TIMEOUT_MS     60000
+struct Lockable::Instance
+{
+    mutable QMutex mutex;
+
+    mutable int lockCount;
+    mutable QMutex countMutex;
 
-Lockable::Lockable() : _mutex(QMutex::Recursive), _lockCount(0)
+    Instance() : mutex(QMutex::Recursive), lockCount(0)
+    {}
+};
+
+Lockable::Lockable() : d(new Instance)
 {}
-        
+
 Lockable::~Lockable()
-{
-    while(_lockCount > 0)
+{    
+    d->countMutex.lock();
+    while(d->lockCount > 0)
     {
-        unlock();
+        d->mutex.unlock();
+        d->lockCount--;
     }
+    d->countMutex.unlock();
+
+    delete d;
 }
 
 void Lockable::lock() const
 {
-    // Acquire the lock.  Blocks until the operation succeeds.
-    if(!_mutex.tryLock(LOCK_TIMEOUT_MS))
-    {
-        /// @throw Error Acquiring the mutex failed due to an error.
-        throw Error("Lockable::lock", "Failed to lock");
-    }
+    d->countMutex.lock();
+    d->lockCount++;
+    d->countMutex.unlock();
 
-    _lockCount++;
+    d->mutex.lock();
 }
 
 void Lockable::unlock() const
 {
-    if(_lockCount > 0)
-    {
-        _lockCount--;
+    // Release the lock.
+    d->mutex.unlock();
 
-        // Release the lock.
-        _mutex.unlock();
-    }
+    d->countMutex.lock();
+    d->lockCount--;
+    d->countMutex.unlock();
+
+    DENG2_ASSERT(d->lockCount >= 0);
 }
 
 bool Lockable::isLocked() const
 {
-    return _lockCount > 0;
+    bool result;
+    d->countMutex.lock();
+    result = (d->lockCount > 0);
+    d->countMutex.unlock();
+    return result;
 }
 
 void Lockable::assertLocked() const
 {
     DENG2_ASSERT(isLocked());
 }
+
+} // namespace de
+