diff --git a/include/lua.h b/include/lua.h
index 769d472..334b2c7 100644
--- a/include/lua.h
+++ b/include/lua.h
@@ -148,7 +148,8 @@ LUA_API lua_Number      (lua_tonumber) (lua_State *L, int idx);
 LUA_API lua_Integer     (lua_tointeger) (lua_State *L, int idx);
 LUA_API int             (lua_toboolean) (lua_State *L, int idx);
 LUA_API const char     *(lua_tolstring) (lua_State *L, int idx, size_t *len);
-LUA_API size_t          (lua_objlen) (lua_State *L, int idx);
+LUA_API size_t          (lua_objlen) (lua_State *L, int idx); // Cobalt-compatible length
+LUA_API size_t          (lua_totalobjlen) (lua_State *L, int idx); // PUC-compatible length
 LUA_API lua_CFunction   (lua_tocfunction) (lua_State *L, int idx);
 LUA_API void	       *(lua_touserdata) (lua_State *L, int idx);
 LUA_API lua_State      *(lua_tothread) (lua_State *L, int idx);
diff --git a/src/lapi.c b/src/lapi.c
index 39bf61b..5a71d84 100644
--- a/src/lapi.c
+++ b/src/lapi.c
@@ -381,6 +381,32 @@ LUA_API size_t lua_objlen (lua_State *L, int idx) {
   }
 }
 
+LUA_API size_t lua_totalobjlen (lua_State *L, int idx) {
+  StkId o = index2adr(L, idx);
+  switch (ttype(o)) {
+    case LUA_TSTRING: return tsvalue(o)->len;
+    case LUA_TUSERDATA: return uvalue(o)->len;
+    case LUA_TTABLE: {
+      Table* t = hvalue(o);
+      size_t n;
+      for (n = t->sizearray; n > 0; --n) {
+        if (ttype(luaH_getnum(t, n)) != LUA_TNIL) {
+          return n;
+        }
+      }
+      return 0;
+    }
+    case LUA_TNUMBER: {
+      size_t l;
+      lua_lock(L);  /* `luaV_tostring' may create a new string */
+      l = (luaV_tostring(L, o) ? tsvalue(o)->len : 0);
+      lua_unlock(L);
+      return l;
+    }
+    default: return 0;
+  }
+}
+
 
 LUA_API lua_CFunction lua_tocfunction (lua_State *L, int idx) {
   StkId o = index2adr(L, idx);
diff --git a/src/lauxlib.c b/src/lauxlib.c
index c9c98e5..a70379e 100644
--- a/src/lauxlib.c
+++ b/src/lauxlib.c
@@ -393,7 +393,7 @@ LUALIB_API int luaL_igetn (lua_State *L, int t, int ictx) {
     }
     lua_pop(L, 2);
   }
-  return (int)lua_objlen(L, t);
+  return (int)lua_totalobjlen(L, t);
 }
 
 #endif
diff --git a/src/ltable.c b/src/ltable.c
index ec84f4f..fced7eb 100644
--- a/src/ltable.c
+++ b/src/ltable.c
@@ -558,21 +558,23 @@ static int unbound_search (Table *t, unsigned int j) {
 ** such that t[i] is non-nil and t[i+1] is nil (and 0 if t[1] is nil).
 */
 int luaH_getn (Table *t) {
-  unsigned int j = t->sizearray;
-  if (j > 0 && ttisnil(&t->array[j - 1])) {
-    /* there is a boundary in the array part: (binary) search for it */
-    unsigned int i = 0;
-    while (j - i > 1) {
-      unsigned int m = (i+j)/2;
-      if (ttisnil(&t->array[m - 1])) j = m;
-      else i = m;
+  /* Algorithm from Cobalt */
+  unsigned int a = t->sizearray;
+  unsigned int n, m = 0;
+  n = a + 1;
+  while (ttype(luaH_getnum(t, n)) != LUA_TNIL) {
+    m = n;
+    n += a + sizenode(t) + 1;
+  }
+  while (n > m + 1) {
+    unsigned int k = (n + m) / 2;
+    if (ttype(luaH_getnum(t, k)) != LUA_TNIL) {
+      m = k;
+    } else {
+      n = k;
     }
-    return i;
   }
-  /* else must find a boundary in hash part */
-  else if (t->node == dummynode)  /* hash part is empty? */
-    return j;  /* that is easy... */
-  else return unbound_search(t, j);
+  return m;
 }
 
 
diff --git a/src/lua.h b/src/lua.h
index 8759ada..75c9692 100644
--- a/src/lua.h
+++ b/src/lua.h
@@ -148,7 +148,8 @@ LUA_API lua_Number      (lua_tonumber) (lua_State *L, int idx);
 LUA_API lua_Integer     (lua_tointeger) (lua_State *L, int idx);
 LUA_API int             (lua_toboolean) (lua_State *L, int idx);
 LUA_API const char     *(lua_tolstring) (lua_State *L, int idx, size_t *len);
-LUA_API size_t          (lua_objlen) (lua_State *L, int idx);
+LUA_API size_t          (lua_objlen) (lua_State *L, int idx); // Cobalt-compatible length
+LUA_API size_t          (lua_totalobjlen) (lua_State *L, int idx); // PUC-compatible length
 LUA_API lua_CFunction   (lua_tocfunction) (lua_State *L, int idx);
 LUA_API void	       *(lua_touserdata) (lua_State *L, int idx);
 LUA_API lua_State      *(lua_tothread) (lua_State *L, int idx);