diff --git a/C/sysbits.c b/C/sysbits.c
index cbe3eed9a..779ce1b5b 100644
--- a/C/sysbits.c
+++ b/C/sysbits.c
@@ -367,7 +367,7 @@ void cputime_interval(Int *now,Int *interval)
 
 #endif
 
-#if defined(__sun__) && defined(__svr4__)
+#if defined(__sun__) && (defined(__svr4__) || defined(__SVR4))
 
 #if HAVE_LIMITS_H
 #include <limits.h>
@@ -812,7 +812,7 @@ p_srandom (void)
 STATIC_PROTO (void InitSignals, (void));
 
 
-#if defined(__svr4__)
+#if (defined(__svr4__) || defined(__SVR4))
 
 #if HAVE_SIGINFO_H
 #include <siginfo.h>
@@ -1200,7 +1200,7 @@ ProcessSIGINT(void)
    that might be
 */
 static RETSIGTYPE
-#if defined(__svr4__)
+#if (defined(__svr4__) || defined(__SVR4))
 HandleSIGINT (int sig, siginfo_t   *x, ucontext_t *y)
 #else
 HandleSIGINT (int sig)
@@ -1238,7 +1238,7 @@ HandleSIGINT (int sig)
 #if !defined(_WIN32)
 /* this routine is called if the system activated the alarm */
 static RETSIGTYPE
-#if defined(__svr4__)
+#if (defined(__svr4__) || defined(__SVR4))
 HandleALRM (int s, siginfo_t   *x, ucontext_t *y)
 #else
 HandleALRM(int s)
@@ -1259,7 +1259,7 @@ HandleALRM(int s)
 
 #if !defined(LIGHT) && !_MSC_VER && !defined(__MINGW32__) && !defined(LIGHT) 
 static RETSIGTYPE
-#if defined(__svr4__)
+#if (defined(__svr4__) || defined(__SVR4))
 ReceiveSignal (int s, siginfo_t   *x, ucontext_t *y)
 #else
 ReceiveSignal (int s)
diff --git a/C/unify.c b/C/unify.c
index f1c55cc4a..0e49a5623 100644
--- a/C/unify.c
+++ b/C/unify.c
@@ -47,9 +47,10 @@ rational_tree_loop(CELL *pt0, CELL *pt0_end, CELL **to_visit0)
 
 loop:
   while (pt0 < pt0_end) {
-    register CELL *ptd0 = ++pt0; 
+    register CELL *ptd0;
     register CELL d0;
 
+    ptd0 = ++pt0; 
     pt0 = ptd0;
     d0 = *ptd0;
     deref_head(d0, rtree_loop_unk);
@@ -139,11 +140,13 @@ OCUnify_complex(register CELL *pt0, register CELL *pt0_end,
 )
 {
 
-  register CELL **to_visit = (CELL **) H;
+  register CELL **to_visit;
 #if SHADOW_HB
-  register CELL *HBREG = HB;
+  register CELL *HBREG;
+  HBREG = HB;
 #endif
 
+  to_visit = (CELL **) H;
  loop:
   while (pt0 < pt0_end) {
     register CELL *ptd0 = ++pt0;
diff --git a/H/Foreign.h b/H/Foreign.h
index a7fbf0588..93378d3d6 100644
--- a/H/Foreign.h
+++ b/H/Foreign.h
@@ -53,9 +53,9 @@
 #define LOAD_DL 1
 #endif
 
-#ifdef sparc
+#if defined(sparc) || defined(__sparc)
 #undef NO_DYN
-#ifndef __svr4__
+#if (!defined(__svr4__) && !defined(__SVR4))
 #define A_OUT 1
 #else
 #ifdef SIMICS
@@ -66,7 +66,7 @@
 #endif
 #endif
 
-#ifdef __svr4__
+#if (defined(__svr4__) || defined(__SVR4))
 #ifndef SIMICS
 #ifdef NO_DYN
 #undef NO_DYN
diff --git a/H/Regs.h b/H/Regs.h
index 4d7e6823c..cc7c1bf62 100644
--- a/H/Regs.h
+++ b/H/Regs.h
@@ -10,7 +10,7 @@
 * File:		Regs.h							 *
 * mods:									 *
 * comments:	YAP abstract machine registers				 *
-* version:      $Id: Regs.h,v 1.4 2001-06-27 15:46:26 vsc Exp $	 *
+* version:      $Id: Regs.h,v 1.5 2001-09-24 18:07:16 vsc Exp $	 *
 *************************************************************************/
 
 
@@ -25,7 +25,7 @@
 #endif
 #endif
 
-#ifdef sparc
+#if defined(sparc) || defined(__sparc)
 #undef  PUSH_REGS
 #undef  PUSH_X
 #endif
diff --git a/H/absmi.h b/H/absmi.h
index 231785dba..0bf277981 100644
--- a/H/absmi.h
+++ b/H/absmi.h
@@ -28,7 +28,7 @@ static char SccsId[] = "%W% %G%";
  */
 #ifdef __GNUC__
 
-#ifdef sparc
+#if defined(sparc) || defined(__sparc)
 #define SHADOW_P       1
 #define SHADOW_Y       1
 #define SHADOW_S       1
diff --git a/H/alloc.h b/H/alloc.h
index a1a27f439..fe68eaf2e 100644
--- a/H/alloc.h
+++ b/H/alloc.h
@@ -102,7 +102,7 @@ void   STD_PROTO(YAP_InitHeap, (void *));
 
 #elif USE_SBRK
 
-#ifdef __svr4__
+#if (defined(__svr4__) || defined(__SVR4))
 #include <unistd.h>
 #elif sun
 #include <sys/types.h>
diff --git a/H/amiops.h b/H/amiops.h
index 54ca76edc..38251455f 100644
--- a/H/amiops.h
+++ b/H/amiops.h
@@ -371,7 +371,9 @@ Int unify(Term t0, Term t1)
     return(TRUE);
   } else {
     while(TR != TR0) {
-      CELL *p = (CELL *)TrailTerm(--TR);
+      CELL *p;
+      --TR;
+      p = (CELL *)TrailTerm(TR);
       RESET_VARIABLE(p);
     }
     return(FALSE);
diff --git a/VC/include/Tags_24bits.h b/VC/include/Tags_24bits.h
index a6ac5c97a..41a235216 100644
--- a/VC/include/Tags_24bits.h
+++ b/VC/include/Tags_24bits.h
@@ -18,7 +18,7 @@
 * Last rev:	December 90						 *
 * mods:									 *
 * comments:	Tag Scheme for machines with 24 bits adresses (m68000)   *
-* version:      $Id: Tags_24bits.h,v 1.4 2001-08-09 14:01:19 vsc Exp $	 *
+* version:      $Id: Tags_24bits.h,v 1.5 2001-09-24 18:07:16 vsc Exp $	 *
 *************************************************************************/
 
      /*   Version for 24 bit	addresses (68000)
diff --git a/VC/include/Tags_32LowTag.h b/VC/include/Tags_32LowTag.h
index bfa5629a4..5c1deef7c 100644
--- a/VC/include/Tags_32LowTag.h
+++ b/VC/include/Tags_32LowTag.h
@@ -18,7 +18,7 @@
 * Last rev:	December 90						 *
 * mods:									 *
 * comments:	Original Tag Scheme for machines with 32 bits adresses   *
-* version:      $Id: Tags_32LowTag.h,v 1.4 2001-08-09 14:01:19 vsc Exp $	 *
+* version:      $Id: Tags_32LowTag.h,v 1.5 2001-09-24 18:07:16 vsc Exp $	 *
 *************************************************************************/
 
 #define TAG_LOW_BITS_32 1
diff --git a/VC/include/Tags_32Ops.h b/VC/include/Tags_32Ops.h
index fb8099fbe..105718f79 100644
--- a/VC/include/Tags_32Ops.h
+++ b/VC/include/Tags_32Ops.h
@@ -18,7 +18,7 @@
 * Last rev:	December 90						 *
 * mods:									 *
 * comments:	Original Tag Scheme for machines with 32 bits adresses   *
-* version:      $Id: Tags_32Ops.h,v 1.4 2001-08-09 14:01:19 vsc Exp $	 *
+* version:      $Id: Tags_32Ops.h,v 1.5 2001-09-24 18:07:16 vsc Exp $	 *
 *************************************************************************/
 
 /*
diff --git a/VC/include/Tags_32bits.h b/VC/include/Tags_32bits.h
index 9c5063161..893cf1a88 100644
--- a/VC/include/Tags_32bits.h
+++ b/VC/include/Tags_32bits.h
@@ -18,7 +18,7 @@
 * Last rev:	December 90						 *
 * mods:									 *
 * comments:	Original Tag Scheme for machines with 32 bits adresses   *
-* version:      $Id: Tags_32bits.h,v 1.4 2001-08-09 14:01:19 vsc Exp $	 *
+* version:      $Id: Tags_32bits.h,v 1.5 2001-09-24 18:07:16 vsc Exp $	 *
 *************************************************************************/
 
 /*    Original version for 32 bit addresses machines,
diff --git a/VC/include/Tags_64bits.h b/VC/include/Tags_64bits.h
index 5034eb6fb..e2e7def7f 100644
--- a/VC/include/Tags_64bits.h
+++ b/VC/include/Tags_64bits.h
@@ -18,7 +18,7 @@
 * Last rev:	December 90						 *
 * mods:									 *
 * comments:	Original Tag Scheme for machines with 32 bits adresses   *
-* version:      $Id: Tags_64bits.h,v 1.4 2001-08-09 14:01:19 vsc Exp $	 *
+* version:      $Id: Tags_64bits.h,v 1.5 2001-09-24 18:07:16 vsc Exp $	 *
 *************************************************************************/
 
 #define TAG_64BITS 1
diff --git a/VC/include/TermExt.h b/VC/include/TermExt.h
index 568fc3204..3f0be74b2 100644
--- a/VC/include/TermExt.h
+++ b/VC/include/TermExt.h
@@ -17,7 +17,7 @@
 * File:		TermExt.h						 *
 * mods:									 *
 * comments:	Extensions to standard terms for YAP			 *
-* version:      $Id: TermExt.h,v 1.4 2001-08-09 14:01:19 vsc Exp $	 *
+* version:      $Id: TermExt.h,v 1.5 2001-09-24 18:07:16 vsc Exp $	 *
 *************************************************************************/
 
 #if USE_OFFSETS
diff --git a/VC/include/Yap.h b/VC/include/Yap.h
index b10a4dccf..33d5e3337 100644
--- a/VC/include/Yap.h
+++ b/VC/include/Yap.h
@@ -17,7 +17,7 @@
 * File:		Yap.h.m4						 *
 * mods:									 *
 * comments:	main header file for YAP				 *
-* version:      $Id: Yap.h,v 1.4 2001-08-09 14:01:20 vsc Exp $	 *
+* version:      $Id: Yap.h,v 1.5 2001-09-24 18:07:16 vsc Exp $	 *
 *************************************************************************/
 
 #include "config.h"
@@ -171,7 +171,7 @@
 /*   */ typedef unsigned long int UInt;
 
 #else
-	error Yap require integer types of the same size as a pointer
+#	error Yap require integer types of the same size as a pointer
 #endif
 
 #if SIZEOF_SHORT_INT==2
@@ -179,7 +179,7 @@
 /*   */ typedef unsigned short int UShort;
 
 #else
-	error Yap requires integer types half the size of a pointer
+#	error Yap requires integer types half the size of a pointer
 #endif
 
 #elif SIZEOF_INT_P==8
@@ -197,7 +197,7 @@
 /*   */ typedef unsigned long long int UInt;
 
 #   else
-	error Yap requires integer types of the same size as a pointer
+#	error Yap requires integer types of the same size as a pointer
 #   endif
 
 #   if SIZEOF_SHORT_INT==4
@@ -209,12 +209,12 @@
 /*   */ typedef short int UShort;
 
 #   else
-	error Yap requires integer types half the size of a pointer
+#	error Yap requires integer types half the size of a pointer
 #   endif
 
 #else
 
-   error Yap requires pointers of size 4 or 8
+#  error Yap requires pointers of size 4 or 8
 
 #endif
 
diff --git a/m4/Tags_32Ops.h.m4 b/m4/Tags_32Ops.h.m4
index e4c21a9d1..13f9d9fb7 100644
--- a/m4/Tags_32Ops.h.m4
+++ b/m4/Tags_32Ops.h.m4
@@ -11,7 +11,7 @@
 * Last rev:	December 90						 *
 * mods:									 *
 * comments:	Original Tag Scheme for machines with 32 bits adresses   *
-* version:      $Id: Tags_32Ops.h.m4,v 1.1.1.1 2001-04-09 19:53:46 vsc Exp $	 *
+* version:      $Id: Tags_32Ops.h.m4,v 1.2 2001-09-24 18:07:16 vsc Exp $	 *
 *************************************************************************/
 
 /*
@@ -71,7 +71,7 @@ are now 1 in compound terms and structures.
 	This allows optimisation of switch_list
 
 */
-#if defined(i386) || defined(sparc) || defined(_POWER)
+#if defined(i386) || defined(sparc) || defined(_POWER) || defined(__sparc)
 #define UNIQUE_TAG_FOR_PAIRS 1
 #endif
 
diff --git a/m4/Tags_64ops.h.m4 b/m4/Tags_64ops.h.m4
index 139022af8..6f366c4ca 100644
--- a/m4/Tags_64ops.h.m4
+++ b/m4/Tags_64ops.h.m4
@@ -11,7 +11,7 @@
 * Last rev:	December 90						 *
 * mods:									 *
 * comments:	Original Tag Scheme for machines with 32 bits adresses   *
-* version:      $Id: Tags_64ops.h.m4,v 1.1.1.1 2001-04-09 19:53:46 vsc Exp $	 *
+* version:      $Id: Tags_64ops.h.m4,v 1.2 2001-09-24 18:07:16 vsc Exp $	 *
 *************************************************************************/
 
 /*
@@ -69,7 +69,7 @@ are now 1 in compound terms and structures.
 	This allows optimisation of switch_list
 
 */
-#if defined(i386) || defined(sparc) || defined(_POWER)	
+#if defined(i386) || defined(sparc) || defined(_POWER) || defined(__sparc)
 #define UNIQUE_TAG_FOR_PAIRS 1
 #endif
 
diff --git a/m4/Yap.h.m4 b/m4/Yap.h.m4
index 1578d16d6..48a4f5cb8 100644
--- a/m4/Yap.h.m4
+++ b/m4/Yap.h.m4
@@ -10,7 +10,7 @@
 * File:		Yap.h.m4						 *
 * mods:									 *
 * comments:	main header file for YAP				 *
-* version:      $Id: Yap.h.m4,v 1.11 2001-09-24 14:06:06 vsc Exp $	 *
+* version:      $Id: Yap.h.m4,v 1.12 2001-09-24 18:07:16 vsc Exp $	 *
 *************************************************************************/
 
 #include "config.h"
@@ -315,7 +315,7 @@ typedef CELL Term;
 #ifdef i386
 #include <x86_locks.h>
 #endif
-#ifdef sparc
+#if defined(sparc) || defined(__sparc)
 #include <sparc_locks.h>
 #endif
 #ifdef mips
@@ -567,7 +567,7 @@ and  RefOfTerm(t) : Term -> DBRef = ...
 	incompatible with the high tag scheme. Linux-ELF also does not like
 	if you place things in the lower addresses (power to the libc people).
 */
-#if (defined(_AIX) || defined(_WIN32) || defined(sparc) || defined(mips) || defined(__FreeBSD__) || defined(_POWER) || defined(IN_SECOND_QUADRANT)) && !defined(TABLING)
+#if (defined(_AIX) || defined(_WIN32) || defined(sparc) || defined(__sparc) || defined(mips) || defined(__FreeBSD__) || defined(_POWER) || defined(IN_SECOND_QUADRANT)) && !defined(TABLING)
 #define USE_LOW32_TAGS 1
 #endif