diff --git a/C/c_interface.c b/C/c_interface.c
index a9ba9e2d0..2745257f8 100755
--- a/C/c_interface.c
+++ b/C/c_interface.c
@@ -2504,7 +2504,7 @@ YAP_Init(YAP_init_args *yap_init)
     Yap_init_local();
 #ifdef YAPOR
     if (worker_id != 0) {
-#if SBA
+#if SBA||ENV_COPY
       /*
 	In the SBA we cannot just happily inherit registers
 	from the other workers
diff --git a/C/init.c b/C/init.c
index c8da8974d..aa94df031 100755
--- a/C/init.c
+++ b/C/init.c
@@ -1205,9 +1205,15 @@ Yap_CloseScratchPad(void)
 #define MAX_INITS 1
 #endif
 
+#if defined(YAPOR) &&  !defined(THREADS)
+struct worker_shared *Yap_global;
+#else
 struct worker_shared Yap_Global;
+#endif
 
-#if defined(YAPOR) || defined(THREADS)
+#if defined(YAPOR) &&  !defined(THREADS)
+struct worker_local	*Yap_WLocal;
+#elif defined(YAPOR) || defined(THREADS)
 struct worker_local	Yap_WLocal[MAX_AGENTS];
 #else
 struct worker_local	Yap_WLocal;
@@ -1259,7 +1265,6 @@ Yap_InitWorkspace(UInt Heap, UInt Stack, UInt Trail, UInt Atts, UInt max_table_s
   int             i;
 
   /* initialise system stuff */
-
 #if PUSH_REGS
 #ifdef THREADS
   pthread_key_create(&Yap_yaamregs_key, NULL);
diff --git a/H/Yap.h b/H/Yap.h
index 46f294835..d6bab29ff 100755
--- a/H/Yap.h
+++ b/H/Yap.h
@@ -361,7 +361,7 @@ typedef CELL Term;
 typedef pthread_mutex_t lockvar;
 typedef pthread_rwlock_t rwlock_t;
 
-#elif defined(i386)
+#elif defined(i386)|| defined(__x86_64__)
 typedef volatile int lockvar;
 #include <locks_x86.h>
 #elif defined(sparc) || defined(__sparc)
diff --git a/H/YapHeap.h b/H/YapHeap.h
index fff158780..ec52098d2 100755
--- a/H/YapHeap.h
+++ b/H/YapHeap.h
@@ -171,11 +171,19 @@ typedef struct various_codes {
 
 #include "hglobals.h"
 
+#if defined(YAPOR) && !defined(THREADS)
+extern struct worker_shared *Yap_global;
+#else
 extern struct worker_shared Yap_Global;
 #define Yap_global (&Yap_Global)
+#endif
 
 #if defined(YAPOR) || defined(THREADS)
+#if defined(THREADS)
 extern struct worker_local	Yap_WLocal[MAX_AGENTS];
+#else
+extern struct worker_local	*Yap_WLocal;
+#endif
 #define WL (Yap_WLocal+worker_id)
 #define FOREIGN_WL(wid) (Yap_WLocal+(wid))
 #else
diff --git a/OPTYap/opt.init.c b/OPTYap/opt.init.c
index 70254370b..1d94e2024 100644
--- a/OPTYap/opt.init.c
+++ b/OPTYap/opt.init.c
@@ -243,14 +243,12 @@ void make_root_frames(void) {
 #endif /* TABLING */
 }
 
-
 #ifdef YAPOR
 void init_workers(void) {
   int proc;
 #ifdef THREADS
   return;
 #endif
-  NOfThreads = number_workers;
 #ifdef ACOW
   if (number_workers > 1) {
     int son;
diff --git a/OPTYap/opt.memory.c b/OPTYap/opt.memory.c
index 344f238f4..bac5ca4cd 100644
--- a/OPTYap/opt.memory.c
+++ b/OPTYap/opt.memory.c
@@ -39,6 +39,7 @@ int fd_mapfile;
 int shm_mapid[MAX_WORKERS + 1];
 #endif /* MEMORY_MAPPING_SCHEME */
 
+static  Int extra_area = 0;
 
 
 /********************************
@@ -98,6 +99,11 @@ void map_memory(long HeapArea, long GlobalLocalArea, long TrailAuxArea, int n_wo
   TrailAuxArea = ADJUST_SIZE(TrailAuxArea);
 
   /* we'll need this later */
+#if defined(YAPOR) && !defined(THREADS)
+  Yap_global = (struct worker_shared *)( mmap_addr  - sizeof(struct worker_shared));
+  Yap_WLocal =  (struct worker_local *)( mmap_addr  - (sizeof(struct worker_shared)+MAX_WORKERS*sizeof(struct worker_local)));
+  extra_area = ADJUST_SIZE_TO_PAGE(sizeof(struct worker_shared)+MAX_WORKERS*sizeof(struct worker_local));
+#endif
   Yap_HeapBase = (ADDR)mmap_addr;
   Yap_GlobalBase = mmap_addr + HeapArea;
 
@@ -113,14 +119,16 @@ void map_memory(long HeapArea, long GlobalLocalArea, long TrailAuxArea, int n_wo
   WorkerArea = ADJUST_SIZE_TO_PAGE(GlobalLocalArea + TrailAuxArea);
   TotalArea = HeapArea + WorkerArea * n_workers;
 #endif /* YAPOR_MODEL */
-
   /* mmap heap area */
 #ifdef MMAP_MEMORY_MAPPING_SCHEME
   /* map total area in a single go */
-  open_mapfile(TotalArea);
-  if ((mmap_addr = mmap((void *) MMAP_ADDR, (size_t) TotalArea, PROT_READ|PROT_WRITE, 
+  open_mapfile(TotalArea+extra_area);
+  if ((mmap_addr = mmap((void *) MMAP_ADDR-extra_area, (size_t) (TotalArea+extra_area), PROT_READ|PROT_WRITE, 
                          MAP_SHARED|MAP_FIXED, fd_mapfile, 0)) == (void *) -1)
     Yap_Error(FATAL_ERROR, TermNil, "mmap error (map_memory)");
+#if defined(YAPOR) && !defined(THREADS)
+  mmap_addr += extra_area;
+#endif
 #else /* SHM_MEMORY_MAPPING_SCHEME */
 /* Most systems are limited regarding what we can allocate */
 #ifdef ACOW
@@ -267,7 +275,7 @@ void remap_memory(void) {
   for (i = 0; i < number_workers; i++) {
     worker_area(i) = remap_addr + ((number_workers + i - worker_id) % number_workers) * WorkerArea;
     if (mmap(worker_area(i), (size_t)WorkerArea, PROT_READ|PROT_WRITE, 
-        MAP_SHARED|MAP_FIXED, fd_mapfile, remap_offset + i * WorkerArea) == (void *) -1)
+        MAP_SHARED|MAP_FIXED, fd_mapfile, remap_offset + i * WorkerArea + extra_area) == (void *) -1)
       Yap_Error(FATAL_ERROR, TermNil, "mmap error (remap_memory)");
   }
 #endif /* MEMORY_MAPPING_SCHEME */