diff --git a/src/lgc.c b/src/lgc.c
index e14a3d2..305347b 100644
--- a/src/lgc.c
+++ b/src/lgc.c
@@ -287,6 +287,7 @@ static void traverserope (global_State *g, TRope *r) {
     if (r->tsr.right->tsr.tt == LUA_TSTRING) stringmark(cast(TString *, r->tsr.right));
     else markobject(g, r->tsr.right);
   }
+  if (r->tsr.res) stringmark(r->tsr.res);
 }
 
 
diff --git a/src/lobject.h b/src/lobject.h
index 32ec197..c8ffe43 100644
--- a/src/lobject.h
+++ b/src/lobject.h
@@ -250,6 +250,7 @@ typedef union TRope {
     union TRope * left;
     union TRope * right;
     size_t len;
+    TString *res;
   } tsr;
 } TRope;
 
diff --git a/src/lstring.c b/src/lstring.c
index 594c398..4287ef3 100644
--- a/src/lstring.c
+++ b/src/lstring.c
@@ -117,6 +117,7 @@ TRope *luaS_concat (lua_State *L, TRope *l, TRope *r) {
   rope->tsr.right = r;
   rope->tsr.len = (l->tsr.tt == LUA_TSTRING ? cast(TString *, l)->tsv.len : (l->tsr.tt == LUA_TSUBSTR ? cast(TSubString *, l)->tss.len : l->tsr.len)) +
                   (r->tsr.tt == LUA_TSTRING ? cast(TString *, r)->tsv.len : (r->tsr.tt == LUA_TSUBSTR ? cast(TSubString *, r)->tss.len : r->tsr.len));
+  rope->tsr.res = NULL;
   return rope;
 }
 
@@ -125,6 +126,7 @@ TString *luaS_build (lua_State *L, TRope *rope) {
   TString *s;
   TRope **stack;
   if (rope->tsr.tt == LUA_TSTRING || rope->tsr.tt == LUA_TSUBSTR) return cast(TString *, rope);
+  if (rope->tsr.res) return rope->tsr.res;
   buffer = cur = luaZ_openspace(L, &G(L)->buff, rope->tsr.len);
   stack = G(L)->ropestack;
   do {
@@ -161,6 +163,7 @@ TString *luaS_build (lua_State *L, TRope *rope) {
     rope = rope->tsr.right;
   } while (stack >= G(L)->ropestack);
   s = luaS_newlstr(L, buffer, cur - buffer);
+  rope->tsr.res = s;
   return s;
 }
 
diff --git a/src/lstrlib.c b/src/lstrlib.c
index e20d2e3..4b13f9a 100644
--- a/src/lstrlib.c
+++ b/src/lstrlib.c
@@ -105,13 +105,18 @@ static int str_upper (lua_State *L) {
 
 static int str_rep (lua_State *L) {
   size_t l;
-  luaL_Buffer b;
+  char * str;
+  void * ud;
   const char *s = luaL_checklstring(L, 1, &l);
-  int n = luaL_checkint(L, 2);
-  luaL_buffinit(L, &b);
-  while (n-- > 0)
-    luaL_addlstring(&b, s, l);
-  luaL_pushresult(&b);
+  int n = luaL_checkint(L, 2), i;
+  if (n == 0) lua_pushliteral(L, "");
+  else if (n == 1) lua_pushvalue(L, 1);
+  else {
+    str = lua_getallocf(L, &ud)(ud, NULL, 0, l * n);
+    for (i = 0; i < n; i++) memcpy(str + (i * l), s, l);
+    lua_pushlstring(L, str, l * n);
+    lua_getallocf(L, &ud)(ud, str, l * n, 0);
+  }
   return 1;
 }