diff --git a/C/init.c b/C/init.c
index b29374532..b09a41ad9 100644
--- a/C/init.c
+++ b/C/init.c
@@ -1139,6 +1139,7 @@ InitThreadHandles(void)
   Yap_heap_regs->thread_handle[0].handle = pthread_self();
   pthread_mutex_init(&ThreadHandle[0].tlock, NULL);
   pthread_mutex_init(&ThreadHandle[0].tlock_status, NULL);
+  Yap_heap_regs->thread_handle[0].tdetach = MkAtomTerm(AtomFalse);
 }
 #endif
 
diff --git a/C/threads.c b/C/threads.c
index d1824b55b..2546d587e 100644
--- a/C/threads.c
+++ b/C/threads.c
@@ -711,7 +711,8 @@ p_thread_atexit(void)
 {				/* '$thread_signal'(+P)	 */
   Term t;
 
-  if (ThreadHandle[worker_id].texit->Entry == MkAtomTerm(AtomTrue)) {
+  if (!ThreadHandle[worker_id].texit ||
+      ThreadHandle[worker_id].texit->Entry == MkAtomTerm(AtomTrue)) {
     return FALSE;
   }
   do {
diff --git a/H/dhstruct.h b/H/dhstruct.h
index adf7c6ec0..ed4a77a4e 100644
--- a/H/dhstruct.h
+++ b/H/dhstruct.h
@@ -45,10 +45,6 @@
 #define WL	wl
 #endif
 #endif
-#ifdef THREADS
-#define ThreadHandlesLock Yap_heap_regs->thread_handles_lock
-#define ThreadHandle Yap_heap_regs->thread_handle
-#endif
 
 #define Yap_HoleSize Yap_heap_regs->hole_size
 #define Yap_av Yap_heap_regs->av_
@@ -329,3 +325,8 @@
 #define ForeignCodeBase Yap_heap_regs->foreign_code_base
 #define ForeignCodeTop Yap_heap_regs->foreign_code_top
 #define ForeignCodeMax Yap_heap_regs->foreign_code_max
+
+#ifdef THREADS
+#define ThreadHandlesLock Yap_heap_regs->thread_handles_lock
+#define ThreadHandle Yap_heap_regs->thread_handle
+#endif 
diff --git a/H/hstruct.h b/H/hstruct.h
index 8ddb8a4aa..2db9a6555 100644
--- a/H/hstruct.h
+++ b/H/hstruct.h
@@ -44,10 +44,6 @@
 #ifndef WL
 #define WL	wl
 #endif
-#endif
-#ifdef THREADS
-  lockvar  thread_handles_lock;
-  struct thandle  thread_handle[MAX_THREADS];
 #endif
 
   UInt  hole_size;
@@ -329,3 +325,8 @@
   ADDR  foreign_code_base;
   ADDR  foreign_code_top;
   ADDR  foreign_code_max;
+
+#ifdef THREADS
+  lockvar  thread_handles_lock;
+  struct thandle  thread_handle[MAX_THREADS];
+#endif 
diff --git a/H/ihstruct.h b/H/ihstruct.h
index 3dcc832e3..9a91fcea4 100644
--- a/H/ihstruct.h
+++ b/H/ihstruct.h
@@ -45,10 +45,6 @@
 #define WL	wl
 #endif
 #endif
-#ifdef THREADS
-  INIT_LOCK(Yap_heap_regs->thread_handles_lock);
-  InitThreadHandles();
-#endif
 
 
 
@@ -329,3 +325,8 @@
   Yap_heap_regs->foreign_code_base = NULL;
   Yap_heap_regs->foreign_code_top = NULL;
   Yap_heap_regs->foreign_code_max = NULL;
+
+#ifdef THREADS
+  INIT_LOCK(Yap_heap_regs->thread_handles_lock);
+  InitThreadHandles();
+#endif 
diff --git a/H/rhstruct.h b/H/rhstruct.h
index 7c2d34ce1..391b75a9a 100644
--- a/H/rhstruct.h
+++ b/H/rhstruct.h
@@ -45,10 +45,6 @@
 #define WL	wl
 #endif
 #endif
-#ifdef THREADS
-  REINIT_LOCK(Yap_heap_regs->thread_handles_lock);
-
-#endif
 
 
 
@@ -329,3 +325,8 @@
 
 
 
+
+#ifdef THREADS
+  REINIT_LOCK(Yap_heap_regs->thread_handles_lock);
+
+#endif 
diff --git a/misc/HEAPFIELDS b/misc/HEAPFIELDS
index e0e0bf738..8b5d82458 100644
--- a/misc/HEAPFIELDS
+++ b/misc/HEAPFIELDS
@@ -46,10 +46,6 @@ worker_local	wl			WorkerLocak			void void
 #define WL	wl
 #endif
 #endif
-#ifdef THREADS
-lockvar		thread_handles_lock	ThreadHandlesLock	MkLock
-struct thandle	thread_handle[MAX_THREADS] ThreadHandle		InitThreadHandles() void
-#endif
 
 /* memory management */
 UInt		hole_size		Yap_HoleSize		void void
@@ -377,3 +373,9 @@ void		*foreign_code_loaded	ForeignCodeLoaded	=NULL RestoreForeignCode()
 ADDR		foreign_code_base	ForeignCodeBase		=NULL void
 ADDR		foreign_code_top	ForeignCodeTop		=NULL void
 ADDR		foreign_code_max	ForeignCodeMax		=NULL void
+
+/* Threads Array */
+#ifdef THREADS
+lockvar		thread_handles_lock	ThreadHandlesLock	MkLock
+struct thandle	thread_handle[MAX_THREADS] ThreadHandle		InitThreadHandles() void
+#endif 
diff --git a/pl/threads.yap b/pl/threads.yap
index a44d039fc..f217df5c1 100644
--- a/pl/threads.yap
+++ b/pl/threads.yap
@@ -41,8 +41,10 @@ volatile(P) :-
 :- initialization('$init_thread0').
 
 '$init_thread0' :-
-	'$no_threads', !,
-	recorda('$thread_alias', [0|main], _).
+	recorda('$thread_alias', [0|main], _),
+	fail.
+'$init_thread0' :-
+	'$no_threads', !.
 '$init_thread0' :-
 	recorda('$thread_defaults', [0, 0, 0, false, true], _),
 	'$create_thread_mq'(0),
@@ -863,7 +865,7 @@ thread_property(Id, Prop) :-
 	;	Status = running
 	).
 '$thread_property'(Id, detached(Detached)) :-
-	'$thread_detached'(Id,Detached).
+	( '$thread_detached'(Id,Detached) -> true ; Detached = false ).
 '$thread_property'(Id, at_exit(M:G)) :-
 	'$thread_run_at_exit'(G,M).
 '$thread_property'(Id, InfoSize) :-