diff --git a/common/JackActivationCount.h b/common/JackActivationCount.h
index 7efc031c..a77e6e6d 100644
--- a/common/JackActivationCount.h
+++ b/common/JackActivationCount.h
@@ -33,7 +33,7 @@ struct JackClientControl;
 \brief Client activation counter.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 class JackActivationCount
 {
 
@@ -74,7 +74,7 @@ class JackActivationCount
             return fValue;
         }
 
-}  POST_PACKED_STRUCTURE;
+};
 
 } // end of namespace
 
diff --git a/common/JackAtomicArrayState.h b/common/JackAtomicArrayState.h
index a2c0139d..16d2f19c 100644
--- a/common/JackAtomicArrayState.h
+++ b/common/JackAtomicArrayState.h
@@ -30,7 +30,7 @@ namespace Jack
 /*!
 \brief Counter for CAS
 */
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 struct AtomicArrayCounter
 {
     union {
@@ -68,7 +68,7 @@ struct AtomicArrayCounter
         return *this;
     }
     
-} POST_PACKED_STRUCTURE;
+};
 
 #define Counter1(e) (e).info.fLongVal
 #define GetIndex1(e, state) ((e).info.scounter.fByteVal[state])
@@ -109,7 +109,7 @@ Requirement:
 
 // CHECK livelock
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 template <class T>
 class JackAtomicArrayState
 {
@@ -249,7 +249,7 @@ class JackAtomicArrayState
             WriteNextStateStopAux(state);
         }
 
-} POST_PACKED_STRUCTURE;
+};
 
 } // end of namespace
 
diff --git a/common/JackAtomicState.h b/common/JackAtomicState.h
index 1eef4e11..ea166c15 100644
--- a/common/JackAtomicState.h
+++ b/common/JackAtomicState.h
@@ -31,7 +31,7 @@ namespace Jack
 \brief Counter for CAS
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 struct AtomicCounter
 {
     union {
@@ -70,7 +70,7 @@ struct AtomicCounter
         return *this;
     }
 
-} POST_PACKED_STRUCTURE;
+};
 
 #define Counter(e) (e).info.fLongVal
 #define CurIndex(e) (e).info.scounter.fShortVal1
@@ -85,7 +85,7 @@ struct AtomicCounter
 
 // CHECK livelock
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 template <class T>
 class JackAtomicState
 {
@@ -254,7 +254,7 @@ class JackAtomicState
         }
         */
         
-} POST_PACKED_STRUCTURE;
+};
 
 } // end of namespace
 
diff --git a/common/JackClientControl.h b/common/JackClientControl.h
index 925f09dd..1bf731d6 100644
--- a/common/JackClientControl.h
+++ b/common/JackClientControl.h
@@ -34,7 +34,7 @@ namespace Jack
 \brief Client control possibly in shared memory.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 struct JackClientControl : public JackShmMemAble
 {
     char fName[JACK_CLIENT_NAME_SIZE + 1];
@@ -88,7 +88,7 @@ struct JackClientControl : public JackShmMemAble
         fSessionID = uuid;
     }
 
-} POST_PACKED_STRUCTURE;
+};
 
 } // end of namespace
 
diff --git a/common/JackConnectionManager.h b/common/JackConnectionManager.h
index 5041557a..23bd0f88 100644
--- a/common/JackConnectionManager.h
+++ b/common/JackConnectionManager.h
@@ -36,7 +36,7 @@ struct JackClientControl;
 \brief Utility class.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 template <int SIZE>
 class JackFixedArray
 {
@@ -117,13 +117,13 @@ class JackFixedArray
             return fCounter;
         }
 
-} POST_PACKED_STRUCTURE;
+};
 
 /*!
 \brief Utility class.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 template <int SIZE>
 class JackFixedArray1 : public JackFixedArray<SIZE>
 {
@@ -154,13 +154,13 @@ class JackFixedArray1 : public JackFixedArray<SIZE>
             }
         }
 
-} POST_PACKED_STRUCTURE;
+};
 
 /*!
 \brief Utility class.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 template <int SIZE>
 class JackFixedMatrix
 {
@@ -250,13 +250,13 @@ class JackFixedMatrix
         }
 
 
-} POST_PACKED_STRUCTURE;
+};
 
 /*!
 \brief Utility class.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 template <int SIZE>
 class JackLoopFeedback
 {
@@ -364,13 +364,13 @@ class JackLoopFeedback
             return -1;
         }
 
-} POST_PACKED_STRUCTURE;
+};
 
 /*!
 \brief For client timing measurements.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 struct JackClientTiming
 {
     jack_time_t fSignaledAt;
@@ -393,7 +393,7 @@ struct JackClientTiming
         fStatus = NotTriggered;
     }
 
-} POST_PACKED_STRUCTURE;
+};
 
 /*!
 \brief Connection manager.
@@ -407,7 +407,7 @@ struct JackClientTiming
 </UL>
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 class SERVER_EXPORT JackConnectionManager
 {
 
@@ -487,7 +487,7 @@ class SERVER_EXPORT JackConnectionManager
         int SuspendRefNum(JackClientControl* control, JackSynchro* table, JackClientTiming* timing, long time_out_usec);
         void TopologicalSort(std::vector<jack_int_t>& sorted);
 
-} POST_PACKED_STRUCTURE;
+};
 
 } // end of namespace
 
diff --git a/common/JackEngineControl.h b/common/JackEngineControl.h
index 254d4a45..c3785198 100644
--- a/common/JackEngineControl.h
+++ b/common/JackEngineControl.h
@@ -47,7 +47,7 @@ typedef JACK_ALIGNED_TYPE(UInt64) jack_UInt64;
 \brief Engine control in shared memory.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 struct SERVER_EXPORT JackEngineControl : public JackShmMem
 {
     // Shared state
@@ -183,7 +183,7 @@ struct SERVER_EXPORT JackEngineControl : public JackShmMem
     void CalcCPULoad(JackClientInterface** table, JackGraphManager* manager, jack_time_t cur_cycle_begin, jack_time_t prev_cycle_end);
     void ResetRollingUsecs();
 
-} POST_PACKED_STRUCTURE;
+};
 
 } // end of namespace
 
diff --git a/common/JackEngineProfiling.h b/common/JackEngineProfiling.h
index 04fdb953..88be1cd5 100644
--- a/common/JackEngineProfiling.h
+++ b/common/JackEngineProfiling.h
@@ -37,7 +37,7 @@ namespace Jack
 \brief Timing stucture for a client.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 struct JackTimingMeasureClient
 {
     int fRefNum;
@@ -54,13 +54,13 @@ struct JackTimingMeasureClient
         fStatus((jack_client_state_t)0)
     {}
     
-} POST_PACKED_STRUCTURE;
+};
 
 /*!
 \brief Timing interval in the global table for a given client
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 struct JackTimingClientInterval
 {
     int fRefNum;
@@ -74,13 +74,13 @@ struct JackTimingClientInterval
          fEndInterval(-1)
     {}
     
-} POST_PACKED_STRUCTURE;
+};
 
 /*!
 \brief Timing stucture for a table of clients.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 struct JackTimingMeasure
 {
     unsigned int fAudioCycle;
@@ -96,7 +96,7 @@ struct JackTimingMeasure
         fPrevCycleEnd(0)
     {}
     
-} POST_PACKED_STRUCTURE;
+};
 
 /*!
 \brief Client timing monitoring.
@@ -105,7 +105,7 @@ struct JackTimingMeasure
 class JackClientInterface;
 class JackGraphManager;
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 class SERVER_EXPORT JackEngineProfiling
 {
 
@@ -132,7 +132,7 @@ class SERVER_EXPORT JackEngineProfiling
                     
         JackTimingMeasure* GetCurMeasure();
 
-} POST_PACKED_STRUCTURE;
+};
 
 } // end of namespace
 
diff --git a/common/JackFilters.h b/common/JackFilters.h
index 6b5f0d32..9f57a577 100644
--- a/common/JackFilters.h
+++ b/common/JackFilters.h
@@ -38,7 +38,7 @@ namespace Jack
 
     #define MAX_SIZE 64
 
-    PRE_PACKED_STRUCTURE
+    /* Note: This class must be kept 32/64 clean! */
     struct JackFilter
     {
 
@@ -64,9 +64,9 @@ namespace Jack
             return mean / MAX_SIZE;
         }
 
-    } POST_PACKED_STRUCTURE;
+    };
 
-    PRE_PACKED_STRUCTURE
+    /* Note: This class must be kept 32/64 clean! */
     class JackDelayLockedLoop
     {
 
@@ -147,9 +147,9 @@ namespace Jack
                 return fCurrentWakeup;
             }
 
-    } POST_PACKED_STRUCTURE;
+    };
 
-    PRE_PACKED_STRUCTURE
+    /* Note: This class must be kept 32/64 clean! */
     class JackAtomicDelayLockedLoop : public JackAtomicState<JackDelayLockedLoop>
     {
          public:
@@ -213,7 +213,7 @@ namespace Jack
 
                 return res;
             }
-    } POST_PACKED_STRUCTURE;
+    };
 
 #endif
 
diff --git a/common/JackFrameTimer.h b/common/JackFrameTimer.h
index a32e7423..13916e1f 100644
--- a/common/JackFrameTimer.h
+++ b/common/JackFrameTimer.h
@@ -32,7 +32,7 @@ namespace Jack
 \brief A structure used for time management.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 class SERVER_EXPORT JackTimer
 {
 
@@ -69,13 +69,13 @@ class SERVER_EXPORT JackTimer
             return fCurrentWakeup;
         }
 
-} POST_PACKED_STRUCTURE;
+};
 
 /*!
 \brief A class using the JackAtomicState to manage jack time.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 class SERVER_EXPORT JackFrameTimer : public JackAtomicState<JackTimer>
 {
 
@@ -97,7 +97,7 @@ class SERVER_EXPORT JackFrameTimer : public JackAtomicState<JackTimer>
         void IncFrameTime(jack_nframes_t buffer_size, jack_time_t callback_usecs, jack_time_t period_usecs);
         void ReadFrameTime(JackTimer* timer);
 
-} POST_PACKED_STRUCTURE;
+};
 
 
 } // end of namespace
diff --git a/common/JackGraphManager.h b/common/JackGraphManager.h
index 15f0275f..9c6d8aad 100644
--- a/common/JackGraphManager.h
+++ b/common/JackGraphManager.h
@@ -36,7 +36,7 @@ namespace Jack
 \brief Graph manager: contains the connection manager and the port array.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 class SERVER_EXPORT JackGraphManager : public JackShmMem, public JackAtomicState<JackConnectionManager>
 {
 
@@ -137,7 +137,7 @@ class SERVER_EXPORT JackGraphManager : public JackShmMem, public JackAtomicState
         static JackGraphManager* Allocate(int port_max);
         static void Destroy(JackGraphManager* manager);
 
-} POST_PACKED_STRUCTURE;
+};
 
 
 } // end of namespace
diff --git a/common/JackPort.h b/common/JackPort.h
index f7a601ed..4198d83c 100644
--- a/common/JackPort.h
+++ b/common/JackPort.h
@@ -35,7 +35,7 @@ namespace Jack
 \brief Base class for port.
 */
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 class SERVER_EXPORT JackPort
 {
 
@@ -113,7 +113,7 @@ class SERVER_EXPORT JackPort
 
         int GetRefNum() const;
 
-} POST_PACKED_STRUCTURE;
+};
 
 } // end of namespace
 
diff --git a/common/JackTransportEngine.h b/common/JackTransportEngine.h
index b6a4ddcf..34846783 100644
--- a/common/JackTransportEngine.h
+++ b/common/JackTransportEngine.h
@@ -89,7 +89,7 @@ We have:
 
 class JackClientInterface;
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 class SERVER_EXPORT JackTransportEngine : public JackAtomicArrayState<jack_position_t>
 {
 
@@ -194,7 +194,7 @@ class SERVER_EXPORT JackTransportEngine : public JackAtomicArrayState<jack_posit
             fNetworkSync = sync;
         }
 
-} POST_PACKED_STRUCTURE;
+};
 
 } // end of namespace
 
diff --git a/common/jack/systemdeps.h b/common/jack/systemdeps.h
index 5e69d303..b104f2a9 100644
--- a/common/jack/systemdeps.h
+++ b/common/jack/systemdeps.h
@@ -20,19 +20,10 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 #ifndef __jack_systemdeps_h__
 #define __jack_systemdeps_h__
 
-#ifndef POST_PACKED_STRUCTURE
+#ifndef JACK_ALIGNED_TYPE
 
     #ifdef __GNUC__
-        /* POST_PACKED_STRUCTURE needs to be a macro which
-           expands into a compiler directive. The directive must
-           tell the compiler to arrange the preceding structure
-           declaration so that it is packed on byte-boundaries rather 
-           than use the natural alignment of the processor and/or
-           compiler.
-        */
 
-        #define PRE_PACKED_STRUCTURE
-        #define POST_PACKED_STRUCTURE __attribute__((__packed__))
 
         #define JACK_ALIGN(N) __attribute__((__aligned__(N)))
 
@@ -42,18 +33,6 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
     #else
     
         #ifdef _MSC_VER
-            #define PRE_PACKED_STRUCTURE1 __pragma(pack(push,1))
-            #define PRE_PACKED_STRUCTURE    PRE_PACKED_STRUCTURE1
-            /* PRE_PACKED_STRUCTURE needs to be a macro which
-            expands into a compiler directive. The directive must
-            tell the compiler to arrange the following structure
-            declaration so that it is packed on byte-boundaries rather
-            than use the natural alignment of the processor and/or
-            compiler.
-            */
-            #define POST_PACKED_STRUCTURE ;__pragma(pack(pop))
-            /* and POST_PACKED_STRUCTURE needs to be a macro which
-            restores the packing to its previous setting */
 
             #define JACK_ALIGN(N) __declspec(align(N))
 
@@ -61,8 +40,6 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
             #define JACK_ALIGNED_TYPE(T) JACK_ALIGN(sizeof(T)) T
 
         #else
-            #define PRE_PACKED_STRUCTURE
-            #define POST_PACKED_STRUCTURE
 
             #define JACK_ALIGN(N)
             #define JACK_ALIGNED_TYPE(T) T
diff --git a/common/jack/types.h b/common/jack/types.h
index 53bef451..eac6aa96 100644
--- a/common/jack/types.h
+++ b/common/jack/types.h
@@ -267,7 +267,7 @@ typedef void (*JackLatencyCallback)(jack_latency_callback_mode_t mode, void *arg
 /**
  * the new latency API operates on Ranges.
  */
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 struct _jack_latency_range
 {
     /**
@@ -278,7 +278,7 @@ struct _jack_latency_range
      * maximum latency
      */
     jack_nframes_t max;
-} POST_PACKED_STRUCTURE;
+};
 
 typedef struct _jack_latency_range jack_latency_range_t;
 
@@ -557,7 +557,7 @@ typedef enum {
 #define JACK_POSITION_MASK (JackPositionBBT|JackPositionTimecode)
 #define EXTENDED_TIME_INFO
 
-PRE_PACKED_STRUCTURE
+/* Note: This class must be kept 32/64 clean! */
 struct _jack_position {
 
     /* these four cannot be set from clients: the server sets them */
@@ -624,7 +624,7 @@ struct _jack_position {
     /* When (unique_1 == unique_2) the contents are consistent. */
     jack_unique_t       unique_2;       /**< unique ID */
 
-} POST_PACKED_STRUCTURE;
+};
 
 typedef struct _jack_position jack_position_t;
 
diff --git a/common/shm.h b/common/shm.h
index 1b4ff29d..057f885e 100644
--- a/common/shm.h
+++ b/common/shm.h
@@ -149,7 +149,7 @@ extern "C"
      * attached to the address space.
      */
 
-    PRE_PACKED_STRUCTURE
+    /* Note: This class must be kept 32/64 clean! */
     struct _jack_shm_info {
         jack_shm_registry_index_t index;       /* offset into the registry */
         uint32_t size;
@@ -157,7 +157,7 @@ extern "C"
             void *attached_at;  /* address where attached */
             char ptr_size[8];
         } ptr;  /* a "pointer" that has the same 8 bytes size when compling in 32 or 64 bits */
-    } POST_PACKED_STRUCTURE;
+    };
     
     typedef struct _jack_shm_info jack_shm_info_t;