diff --git a/DOCUMENTATION.mkd b/DOCUMENTATION.mkd
index 46ecd92..796a021 100644
--- a/DOCUMENTATION.mkd
+++ b/DOCUMENTATION.mkd
@@ -28,16 +28,19 @@ tinycdb library reports an error.
 
 Returns an iterator function.
 
-## `cdb.make(destination, temporary)`
+## `cdb.make(destination, temporary, [overwrite])`
 Create a cdb maker. Upon calling `maker:finish()`, the temporary file will be
 renamed to the destination, replacing it atomically. This function fails if the
-temporary file already exists. If you allow maker to be garbage collected
+temporary file already exists unless overwrite is set to true in wich case the
+temporary file is overwriten. If you allow maker to be garbage collected
 without calling finish(), the temporary file will be left behind.
 
 Takes the parameters:
 
 * `destination` the destination filename.
 * `temporary` the name of the file to be used while the cdb is being constructed
+* `overwrite` optional, boolean indicating if the temporary file should be overwritten
+   if it exists.
 
 Returns an instance of `cdb.make` or `nil` plus an error message.
 
diff --git a/Makefile b/Makefile
index cb992d1..3ca055b 100644
--- a/Makefile
+++ b/Makefile
@@ -8,7 +8,7 @@ LUABIN= $(LUA)/bin
 
 # probably no need to change anything below here
 CC= gcc
-CFLAGS= $(INCS) $(WARN) -O2
+CFLAGS= $(INCS) $(WARN) -O2 -fPIC
 WARN= -Wall
 INCS= -I$(LUAINC)
 
diff --git a/lcdb.c b/lcdb.c
index 0e68dce..3fcdbe5 100644
--- a/lcdb.c
+++ b/lcdb.c
@@ -143,7 +143,7 @@ static int lcdbm_iternext(lua_State *L) {
 
 /* for k, v in db:pairs() do ... end */
 static int lcdbm_pairs(lua_State *L) {
-  struct cdb *cdbp = check_cdb(L, 1);
+  struct cdb *__attribute__ ((unused))cdbp = check_cdb(L, 1);
 
   unsigned pos;
   cdb_seqinit(&pos, cdbp);
@@ -157,7 +157,7 @@ static struct cdb_make *new_cdb_make(lua_State *L) {
   luaL_getmetatable(L, LCDB_MAKE);
   lua_setmetatable(L, -2);
   lua_newtable(L);
-  lua_setfenv(L, 1);
+  lua_setuservalue(L, -2);
   return cdbmp;
 }
 
@@ -167,15 +167,20 @@ static struct cdb_make *check_cdb_make(lua_State *L, int n) {
   return cdbmp;
 }
 
-/* cdb.make(destination, temporary) */
+/* cdb.make(destination, temporary, [overwrite]) */
 static int lcdb_make(lua_State *L) {
   int fd;
   int ret;
   struct cdb_make *cdbmp;
   const char *dest = luaL_checkstring(L, 1);
   const char *tmpname = luaL_checkstring(L, 2);
+  int overwrite = lua_toboolean(L, 3);
+  int flags = O_RDWR|O_CREAT|O_EXCL|O_BINARY;
+
+  if (overwrite)
+      flags &= ~O_EXCL;
 
-  fd = open(tmpname, O_RDWR|O_CREAT|O_EXCL|O_BINARY, 0666);
+  fd = open(tmpname, flags, 0666);
   if (fd < 0)
     return push_errno(L, errno);
 
@@ -183,7 +188,7 @@ static int lcdb_make(lua_State *L) {
   ret = cdb_make_start(cdbmp, fd);
 
   /* store destination and tmpname in userdata environment */
-  lua_getfenv(L, -1);
+  lua_getuservalue(L, -1);
   lua_pushstring(L, dest);
   lua_setfield(L, -2, "dest");
   lua_pushstring(L, tmpname);
@@ -199,10 +204,11 @@ static int lcdbmakem_gc(lua_State *L) {
   struct cdb_make *cdbmp = luaL_checkudata(L, 1, LCDB_MAKE);
 
   if (cdbmp->cdb_fd >= 0) {
+    cdb_make_finish(cdbmp);
     close(cdbmp->cdb_fd);
-    cdb_make_free(cdbmp);
     cdbmp->cdb_fd = -1;
   }
+
   return 0;
 }
 
@@ -237,7 +243,7 @@ static int lcdbmakem_add(lua_State *L) {
 static int lcdbmakem_finish(lua_State *L) {
   struct cdb_make *cdbmp = check_cdb_make(L, 1);
   /* retrieve destination, current filename */
-  lua_getfenv(L, -1);
+  lua_getuservalue(L, -1);
   lua_getfield(L, -1, "dest");
   const char *dest = lua_tostring(L, -1);
   lua_getfield(L, -2, "tmpname");
@@ -246,7 +252,6 @@ static int lcdbmakem_finish(lua_State *L) {
 
   if (cdb_make_finish(cdbmp) < 0 || fsync(cdb_fileno(cdbmp)) < 0 || 
       close(cdb_fileno(cdbmp)) < 0 || rename(tmpname, dest) < 0) {
-    cdb_make_free(cdbmp); /* in case cdb_make_finish failed before freeing */
     cdbmp->cdb_fd = -1;
     return luaL_error(L, strerror(errno));
   }
@@ -285,15 +290,13 @@ int luaopen_cdb(lua_State *L) {
   luaL_newmetatable(L, LCDB_DB);
   lua_pushvalue(L, -1);
   lua_setfield(L, -2, "__index");
-  luaL_register(L, NULL, lcdb_m);
+  luaL_setfuncs(L, lcdb_m, 0);
 
   luaL_newmetatable(L, LCDB_MAKE);
   lua_pushvalue(L, -1);
   lua_setfield(L, -2, "__index");
-  luaL_register(L, NULL, lcdbmake_m);
-
-  lua_newtable(L);
-  luaL_register(L, NULL, lcdb_f);
+  luaL_setfuncs(L, lcdbmake_m, 0);
 
+  luaL_newlib(L, lcdb_f);
   return 1;
 }