diff --git a/lmem.c b/lmem.c
index ccf1a4a8..a1379f24 100644
--- a/lmem.c
+++ b/lmem.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lmem.c,v 1.8 1999/01/22 17:28:00 roberto Exp roberto $
+** $Id: lmem.c,v 1.9 1999/01/22 18:08:57 roberto Exp roberto $
 ** Interface to Memory Manager
 ** See Copyright Notice in lua.h
 */
@@ -24,6 +24,8 @@
 
 
 
+#ifndef DEBUG
+
 int luaM_growaux (void **block, unsigned long nelems, int size,
                        char *errormsg, unsigned long limit) {
   if (nelems >= limit)
@@ -36,9 +38,6 @@ int luaM_growaux (void **block, unsigned long nelems, int size,
 }
 
 
-
-#ifndef DEBUG
-
 /*
 ** generic allocation routine.
 */
@@ -64,6 +63,18 @@ void *luaM_realloc (void *block, unsigned long size) {
 #include <string.h>
 
 
+int luaM_growaux (void **block, unsigned long nelems, int size,
+                       char *errormsg, unsigned long limit) {
+  if (nelems >= limit)
+    lua_error(errormsg);
+  nelems = nelems+1;
+  if (nelems > limit)
+    nelems = limit;
+  *block = luaM_realloc(*block, nelems*size);
+  return (int)nelems;
+}
+
+
 #define HEADER	(sizeof(double))
 
 #define MARK    55
diff --git a/lopcodes.h b/lopcodes.h
index 886d31d1..f1d6a2e1 100644
--- a/lopcodes.h
+++ b/lopcodes.h
@@ -1,5 +1,5 @@
 /*
-** $Id: lopcodes.h,v 1.25 1999/02/09 18:01:55 roberto Exp roberto $
+** $Id: lopcodes.h,v 1.26 1999/02/23 13:38:38 roberto Exp roberto $
 ** Opcodes for Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -107,7 +107,9 @@ SETLINEW,/*	w	-		-		LINE=w  */
 SETLINE,/*	b	-		-		LINE=b  */
 
 LONGARGW,/*	w	(add w*(1<<16) to arg of next instruction) */
-LONGARG /*	b	(add b*(1<<16) to arg of next instruction) */
+LONGARG,/*	b	(add b*(1<<16) to arg of next instruction) */
+
+CHECKSTACK /*	b  (assert #temporaries == b; only for internal debuging!) */
 
 } OpCode;
 
diff --git a/lparser.c b/lparser.c
index 2bd65ee3..03e05102 100644
--- a/lparser.c
+++ b/lparser.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lparser.c,v 1.20 1999/02/09 18:01:55 roberto Exp roberto $
+** $Id: lparser.c,v 1.21 1999/02/24 15:37:19 roberto Exp roberto $
 ** LL(1) Parser and code generator for Lua
 ** See Copyright Notice in lua.h
 */
@@ -403,6 +403,10 @@ static void close_exp (LexState *ls, int pc, int nresults) {
       deltastack(ls, nresults);  /* push results */
     deltastack(ls, -(code[pc]+1));  /* pop params (at code[pc]) and function */
   }
+#ifdef DEBUG
+  if (nresults != MULT_RET)
+    code_oparg(ls, CHECKSTACK, ls->fs->stacksize, 0);
+#endif
 }
 
 
diff --git a/lvm.c b/lvm.c
index 5eee2799..fb8e87bc 100644
--- a/lvm.c
+++ b/lvm.c
@@ -1,5 +1,5 @@
 /*
-** $Id: lvm.c,v 1.49 1999/02/09 18:01:55 roberto Exp roberto $
+** $Id: lvm.c,v 1.50 1999/02/23 13:38:38 roberto Exp roberto $
 ** Lua virtual machine
 ** See Copyright Notice in lua.h
 */
@@ -643,6 +643,10 @@ StkId luaV_execute (Closure *cl, TProtoFunc *tf, StkId base) {
         aux = highbyte(highbyte(aux));
         goto switchentry;  /* do not reset "aux" */
 
+      case CHECKSTACK: aux = *pc++;
+        LUA_ASSERT((S->top-S->stack)-base == aux, "wrong stack size");
+        break;
+
     }
   }
 }