diff --git a/cachegrind/cg_main.c b/cachegrind/cg_main.c
index 059df5be1..e2bd63b66 100644
--- a/cachegrind/cg_main.c
+++ b/cachegrind/cg_main.c
@@ -45,7 +45,6 @@ typedef struct {
 /*--- Constants                                            ---*/
 /*------------------------------------------------------------*/
 
-#define MAX_x86_INSTR_SIZE    16    // According to ia32 sw dev manual vol 2
 #define MIN_LINE_SIZE         16
 #define FILE_LEN              256
 #define FN_LEN                256
@@ -431,8 +430,8 @@ void end_of_x86_instr(UCodeBlock* cb, instr_info* i_node, Bool bb_seen_before,
            t_data_addr1 = INVALID_TEMPREG,
            t_data_addr2 = INVALID_TEMPREG;
 
-   sk_assert(instr_size >= 1 && 
-             instr_size <= MAX_x86_INSTR_SIZE);
+   sk_assert(instr_size >= MIN_INSTR_SIZE && 
+             instr_size <= MAX_INSTR_SIZE);
 
 #define IS_(X)      (INVALID_TEMPREG != t_##X##_addr)
 #define INV(qqt)    (INVALID_TEMPREG == (qqt))
diff --git a/coregrind/vg_errcontext.c b/coregrind/vg_errcontext.c
index f61668b7f..ae1c2927d 100644
--- a/coregrind/vg_errcontext.c
+++ b/coregrind/vg_errcontext.c
@@ -361,7 +361,8 @@ static void gen_suppression(Error* err)
    i = 0;
    do {
       Addr eip = ec->eips[i];
-      if (i > 0) eip--;                 /* point to calling line */
+      if (i > 0) 
+         eip -= MIN_INSTR_SIZE;     // point to calling line
       if ( VG_(get_fnname_nodemangle) (eip, buf,  M_VG_ERRTXT) ) {
          // Stop after "main";  if main() is recursive, stop after last main().
 
diff --git a/coregrind/vg_symtab2.c b/coregrind/vg_symtab2.c
index a250d4abb..9df9f8364 100644
--- a/coregrind/vg_symtab2.c
+++ b/coregrind/vg_symtab2.c
@@ -2226,7 +2226,8 @@ void VG_(mini_stack_dump) ( Addr eips[], UInt n_eips )
    i = 0;
    do {
       Addr eip = eips[i];
-      if (i  > 0) eip--;            /* point to calling line */
+      if (i > 0) 
+         eip -= MIN_INSTR_SIZE;     // point to calling line
       VG_(describe_eip)(eip, buf, M_VG_ERRTXT);
 
       if ( ! VG_(clo_show_below_main)) {
diff --git a/include/x86/tool_arch.h b/include/x86/tool_arch.h
index 2e10c75c3..272e2fa39 100644
--- a/include/x86/tool_arch.h
+++ b/include/x86/tool_arch.h
@@ -35,7 +35,10 @@
 #define FIRST_ARCH_REG  R_EAX
 #define LAST_ARCH_REG   R_EDI
 
-#define N_ARCH_REGS     8
+#define N_ARCH_REGS        8
+
+#define MIN_INSTR_SIZE     1
+#define MAX_INSTR_SIZE    16
 
 #endif   // __X86_TOOL_ARCH_H