diff --git a/3rd/lua/lfunc.c b/3rd/lua/lfunc.c
index 57b63547..250c85f7 100644
--- a/3rd/lua/lfunc.c
+++ b/3rd/lua/lfunc.c
@@ -301,7 +301,7 @@ const char *luaF_getlocalname (const Proto *f, int local_number, int pc) {
 
 void luaF_shareproto (Proto *f) {
   int i;
-  if (f == NULL)
+  if (f == NULL || isshared(f))
     return;
   makeshared(f);
   luaS_share(f->source);
diff --git a/3rd/lua/lstring.c b/3rd/lua/lstring.c
index 935e96a3..195534ac 100644
--- a/3rd/lua/lstring.c
+++ b/3rd/lua/lstring.c
@@ -57,7 +57,7 @@ int luaS_eqshrstr (TString *a, TString *b) {
 }
 
 void luaS_share (TString *ts) {
-  if (ts == NULL)
+  if (ts == NULL || isshared(ts))
     return;
   makeshared(ts);
   ts->id = ATOM_DEC(&STRID);
diff --git a/lualib-src/lua-sharetable.c b/lualib-src/lua-sharetable.c
index 185a5e85..8a84e7bf 100644
--- a/lualib-src/lua-sharetable.c
+++ b/lualib-src/lua-sharetable.c
@@ -41,6 +41,7 @@ mark_shared(lua_State *L) {
 				} else if (!lua_iscfunction(L, idx)) {
 					LClosure *f = (LClosure *)lua_topointer(L, idx);
 					makeshared(f);
+					lua_sharefunction(L, idx);
 				}
 				break;
 			case LUA_TSTRING: