diff --git a/common/JackClientControl.h b/common/JackClientControl.h
index e9e9ce5a..98cd89d4 100644
--- a/common/JackClientControl.h
+++ b/common/JackClientControl.h
@@ -56,9 +56,6 @@ struct JackClientControl : public JackShmMem
         Init("", -1);
     }
 
-    virtual ~JackClientControl()
-    {}
-
     void Init(const char* name, int refnum)
     {
         strcpy(fName, name);
diff --git a/common/JackEngine.cpp b/common/JackEngine.cpp
index d70bca93..ac64e49e 100644
--- a/common/JackEngine.cpp
+++ b/common/JackEngine.cpp
@@ -33,7 +33,15 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 namespace Jack
 {
 
-JackEngine::JackEngine(JackGraphManager* manager, JackSynchro** table, JackEngineControl* control, JackSyncInterface* signal, bool sync, long time_out_ms, bool rt, long priority, bool ve)
+JackEngine::JackEngine(JackGraphManager* manager, 
+						JackSynchro** table, 
+						JackEngineControl* control,
+						JackSyncInterface* signal, 
+						bool sync, 
+						long time_out_ms, 
+						bool rt, 
+						long priority, 
+						bool ve)
 {
     fGraphManager = manager;
     fSynchroTable = table;
diff --git a/common/JackShmMem.cpp b/common/JackShmMem.cpp
index 5fe9826f..29b2b9c6 100644
--- a/common/JackShmMem.cpp
+++ b/common/JackShmMem.cpp
@@ -29,7 +29,7 @@ unsigned long JackShmMem::fSegmentNum = 0;
 unsigned long JackShmMem::fSegmentCount = 0;
 
 jack_shm_info_t JackShmMem::gInfo;
-size_t JackLockMem::gSize = 0;
+size_t JackMem::gSize = 0;
 
 void* JackShmMem::operator new(size_t size)
 {
@@ -62,7 +62,9 @@ void* JackShmMem::operator new(size_t size)
     // It is unsafe to set object fields directly (may be overwritten during object initialization),
     // so use an intermediate global data
     gInfo.index = info.index;
+	gInfo.size = size;
     gInfo.attached_at = info.attached_at;
+	
     JackLog("JackShmMem::new index = %ld attached = %x size = %ld \n", info.index, info.attached_at, size);
     return obj;
 
@@ -89,5 +91,38 @@ void JackShmMem::operator delete(void* p, size_t size)
     }
 }
 
+void LockMemoryImp(void* ptr, size_t size) 
+{
+#ifdef __APPLE__
+	int res = mlock(ptr, size);
+#elif linux_
+	int res = mlock(ptr, size);
+#elif WIN32
+	int res = VirtualLock(ptr, size);
+#endif
+	if (res != 0) {
+		jack_error("Cannot lock down memory area (%s)", strerror(errno));
+	} else {
+		JackLog("Succeeded in locking %u byte memory area\n", size);
+	}
+}
+
+void UnlockMemoryImp(void* ptr, size_t size) 
+{
+#ifdef __APPLE__
+	int res = munlock(ptr, size);
+#elif linux_
+	int res = munlock(ptr, size);
+#elif WIN32
+	int res = VirtualUnlock(ptr, size);
+#endif
+	if (res != 0) {
+		jack_error("Cannot unlock down memory area (%s)", strerror(errno));
+	} else {
+		JackLog("Succeeded in unlocking %u byte memory area\n", size);
+	}
+}
+
+
 } // end of namespace
 
diff --git a/common/JackShmMem.h b/common/JackShmMem.h
index 5ebb55d0..9b51e8cc 100644
--- a/common/JackShmMem.h
+++ b/common/JackShmMem.h
@@ -38,7 +38,10 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 namespace Jack
 {
 
-class JackLockMem
+void LockMemoryImp(void* ptr, size_t size);
+void UnlockMemoryImp(void* ptr, size_t size);
+
+class JackMem
 {
 	private:
 
@@ -50,7 +53,7 @@ class JackLockMem
         void* operator new(size_t size)
 		{	
 			gSize = size;
-			return malloc(size);
+			return calloc(1, size);
 		}
 		
         void operator delete(void* ptr, size_t size)
@@ -58,49 +61,36 @@ class JackLockMem
 			free(ptr);
 		}
 
-        JackLockMem():fSize(gSize)
+        JackMem():fSize(gSize)
         {}
 
-        virtual ~JackLockMem()
+        virtual ~JackMem()
         {
-			UnlockMemory();
+			UnlockMemoryImp(this, fSize);
 		}
 		
-		void LockMemory() 
+		void LockMemory()
 		{
-		#ifdef __APPLE__
-			mlock(this, fSize);
-		#elif linux_
-			mlock(this, fSize);
-		#elif WIN32
-			VirtualLock(this, fSize);
-		#endif
+			LockMemoryImp(this, fSize);
 		}
 		
-		void UnlockMemory() 
+		void UnlockMemory()
 		{
-		#ifdef __APPLE__
-			munlock(this, fSize);
-		#elif linux_
-			munlock(this, fSize);
-		#elif WIN32
-			VirtualUnlock(this, fSize);
-		#endif
+			UnlockMemoryImp(this, fSize);
 		}
 
 };
 
-
 /*!
 \brief The base class for shared memory management.
  
 A class which objects need to be allocated in shared memory derives from this class.
 */
 
-class JackShmMem
+class JackShmMem 
 {
 
-    private:
+    protected:
 
         jack_shm_info_t fInfo;
         static unsigned long fSegmentNum;
@@ -115,11 +105,14 @@ class JackShmMem
         JackShmMem()
         {
             fInfo.index = gInfo.index;
-            fInfo.attached_at = gInfo.attached_at;
-        }
+			fInfo.attached_at = gInfo.attached_at;
+			fInfo.size = gInfo.size;
+		}
 
         virtual ~JackShmMem()
-        {}
+        {
+			UnlockMemoryImp(this, fInfo.size);
+		}
 
         int GetShmIndex()
         {
@@ -130,6 +123,16 @@ class JackShmMem
         {
             return (char*)fInfo.attached_at;
         }
+		
+		void LockMemory()
+		{
+			LockMemoryImp(this, fInfo.size);
+		}
+		
+		void UnlockMemory()
+		{
+			UnlockMemoryImp(this, fInfo.size);
+		}
 
 };
 
diff --git a/common/shm.h b/common/shm.h
index 2ef29fc4..d8256e0d 100644
--- a/common/shm.h
+++ b/common/shm.h
@@ -117,7 +117,8 @@ extern "C"
      */
     typedef struct _jack_shm_info {
         jack_shm_registry_index_t index;       /* offset into the registry */
-        void	*attached_at; /* address where attached */
+		size_t size;
+        void *attached_at; /* address where attached */
     }
     jack_shm_info_t;