diff --git a/ChangeLog b/ChangeLog
index 88223b3d..9c8461ef 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -23,6 +23,10 @@ Michael Voigt
   Jackdmp changes log
 ---------------------------
 
+2008-10-08 Stephane Letz  <letz@grame.fr>
+	
+	* Fix a SMP related bug introduced in rev 2957 : remove the __SMP__ flag and define LOCK for SMP in all cases.
+
 2008-10-02 Stephane Letz  <letz@grame.fr>
 	
 	* Correct file permission for jack-shm-registry POSIX shared memory segment.
diff --git a/common/JackAtomic.h b/common/JackAtomic.h
index 1da0cb63..481e17f3 100644
--- a/common/JackAtomic.h
+++ b/common/JackAtomic.h
@@ -21,7 +21,6 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 #define __JackAtomic__
 
 #include "JackTypes.h"
-
 #include "JackAtomic_os.h"
 
 static inline long INC_ATOMIC(volatile SInt32* val)
diff --git a/linux/JackAtomic_os.h b/linux/JackAtomic_os.h
index 4b62d220..b69cb22a 100644
--- a/linux/JackAtomic_os.h
+++ b/linux/JackAtomic_os.h
@@ -52,11 +52,7 @@ static inline int CAS(register UInt32 value, register UInt32 newvalue, register
 
 #if defined(__i386__) || defined(__x86_64__)
 
-#ifdef __SMP__
-#	define LOCK "lock ; "
-#else
-#	define LOCK ""
-#endif
+#define LOCK "lock ; "
 
 static inline char CAS(volatile UInt32 value, UInt32 newvalue, volatile void* addr)
 {
diff --git a/macosx/JackAtomic_os.h b/macosx/JackAtomic_os.h
index f02fad47..bd88a223 100644
--- a/macosx/JackAtomic_os.h
+++ b/macosx/JackAtomic_os.h
@@ -52,11 +52,7 @@ static inline int CAS(register UInt32 value, register UInt32 newvalue, register
 
 #if defined(__i386__) || defined(__x86_64__)
 
-#ifdef __SMP__
-#	define LOCK "lock ; "
-#else
-#	define LOCK ""
-#endif
+#define LOCK "lock ; "
 
 static inline char CAS(volatile UInt32 value, UInt32 newvalue, volatile void* addr)
 {
diff --git a/windows/JackAtomic_os.h b/windows/JackAtomic_os.h
index 38947437..0a393f7a 100644
--- a/windows/JackAtomic_os.h
+++ b/windows/JackAtomic_os.h
@@ -55,11 +55,7 @@ inline char CAS(volatile UInt32 value, UInt32 newvalue, volatile void * addr)
 
 #else
 
-#ifdef __SMP__
-#	define LOCK "lock ; "
-#else
-#	define LOCK ""
-#endif
+#define LOCK "lock ; "
 
 static inline char CAS(volatile UInt32 value, UInt32 newvalue, volatile void* addr)
 {
diff --git a/wscript b/wscript
index afbc5e69..351f126f 100644
--- a/wscript
+++ b/wscript
@@ -105,7 +105,6 @@ def configure(conf):
 
     conf.define('ADDON_DIR', os.path.normpath(conf.env['PREFIX'] + '/lib/jack'))
     conf.define('JACK_LOCATION', os.path.normpath(conf.env['PREFIX'] + '/bin'))
-    conf.define('__SMP__', 1)
     conf.define('USE_POSIX_SHM', 1)
     conf.define('JACKMP', 1)
     if conf.env['BUILD_JACKDBUS'] == True: