diff --git a/C/computils.c b/C/computils.c
index 6c9b7e22f..c1bd08fa7 100644
--- a/C/computils.c
+++ b/C/computils.c
@@ -146,7 +146,7 @@ AllocCMem (UInt size, struct intermediates *cip)
   char *p;
   if (ASP <= CellPtr (cip->freep) + 256) {
     CACHE_REGS
-    LOCAL_Error_Size = 256+((char *)cip->freep - (char *)H);
+    LOCAL_Error_Size = 256+((char *)cip->freep - (char *)HR);
     save_machine_regs();
     siglongjmp(cip->CompilerBotch, OUT_OF_STACK_BOTCH);
   } 
@@ -856,12 +856,12 @@ void
 Yap_ShowCode (struct intermediates *cint)
 {
   CACHE_REGS
-  CELL *oldH = H;
+  CELL *oldH = HR;
   struct PSEUDO *cpc;
 
   cpc = cint->CodeStart;
   /* MkIntTerm and friends may build terms in the global stack */
-  H = (CELL *)cint->freep;
+  HR = (CELL *)cint->freep;
   while (cpc) {
     compiler_vm_op ic = cpc->op;
     if (ic != nop_op) {
@@ -870,7 +870,7 @@ Yap_ShowCode (struct intermediates *cint)
     cpc = cpc->nextInst;
   }
   Yap_DebugErrorPutc ('\n');
-  H = oldH;
+  HR = oldH;
 }
 
 #endif /* DEBUG */
diff --git a/C/heapgc.c b/C/heapgc.c
index f94523c9b..a1d29d0b4 100644
--- a/C/heapgc.c
+++ b/C/heapgc.c
@@ -1010,7 +1010,7 @@ static void
 inc_vars_of_type(CELL *curr,gc_types val) {
   if (curr >= H0 && curr < TrueHB) {
     old_vars++;
-  } else if (curr >= TrueHB && curr < H) {
+  } else if (curr >= TrueHB && curr < HR) {
     new_vars++;
   } else {
     return;
@@ -2371,7 +2371,7 @@ mark_choicepoints(register choiceptr gc_B, tr_fr_ptr saved_TR, int very_verbose
       case _count_trust_me:
       case _retry:
       case _trust:
-	if (IN_BETWEEN(H0,(CELL *)(gc_B->cp_ap),H)) {
+	if (IN_BETWEEN(H0,(CELL *)(gc_B->cp_ap),HR)) {
 	  fprintf(stderr,"OOPS in GC: gc not supported in this case!!!\n");
 	  exit(1);
 	}
@@ -3895,7 +3895,7 @@ compaction_phase(tr_fr_ptr old_TR, CELL *current_env, yamop *curp USES_REGS)
 	-LOCAL_total_smarked
 #endif
 	!= LOCAL_iptop-(CELL_PTR *)H && LOCAL_iptop < (CELL_PTR *)ASP -1024)
-      fprintf(GLOBAL_stderr,"%% Oops on LOCAL_iptop-H (%ld) vs %ld\n", (unsigned long int)(LOCAL_iptop-(CELL_PTR *)H), LOCAL_total_marked);
+      fprintf(GLOBAL_stderr,"%% Oops on LOCAL_iptop-H (%ld) vs %ld\n", (unsigned long int)(LOCAL_iptop-(CELL_PTR *)HR), LOCAL_total_marked);
     */
 #endif
 #if DEBUGX