diff --git a/3rd/lua/lgc.c b/3rd/lua/lgc.c
index e7e1bbe6..e90766dc 100644
--- a/3rd/lua/lgc.c
+++ b/3rd/lua/lgc.c
@@ -80,9 +80,9 @@
   (x->marked = cast_byte((x->marked & ~WHITEBITS) | bitmask(BLACKBIT)))
 
 
-#define valiswhite(x)   (iscollectable(x) && iswhite(gcvalue(x)))
+#define valiswhite(x)   (iscollectable(x) && ispurewhite(gcvalue(x)))
 
-#define keyiswhite(n)   (keyiscollectable(n) && iswhite(gckey(n)))
+#define keyiswhite(n)   (keyiscollectable(n) && ispurewhite(gckey(n)))
 
 
 /*
@@ -96,7 +96,7 @@
 
 #define markkey(g, n)	{ if keyiswhite(n) reallymarkobject(g,gckey(n)); }
 
-#define markobject(g,t)	{ if (iswhite(t)) reallymarkobject(g, obj2gco(t)); }
+#define markobject(g,t)	{ if (ispurewhite(t)) reallymarkobject(g, obj2gco(t)); }
 
 /*
 ** mark an object that can be NULL (either because it is really optional,
@@ -188,7 +188,7 @@ static int iscleared (global_State *g, const GCObject *o) {
     markobject(g, o);  /* strings are 'values', so are never weak */
     return 0;
   }
-  else return iswhite(o);
+  else return ispurewhite(o);
 }
 
 
@@ -289,8 +289,6 @@ GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) {
 ** (only closures can), and a userdata's metatable must be a table.
 */
 static void reallymarkobject (global_State *g, GCObject *o) {
-  if (isshared(o))
-    return;
   switch (o->tt) {
     case LUA_VSHRSTR:
     case LUA_VLNGSTR: {
diff --git a/3rd/lua/lgc.h b/3rd/lua/lgc.h
index eb00bcf8..62a44e1a 100644
--- a/3rd/lua/lgc.h
+++ b/3rd/lua/lgc.h
@@ -120,6 +120,7 @@
 
 #define isshared(x)     (getage(x) == G_SHARED)
 #define makeshared(x)   setage(x, G_SHARED)
+#define ispurewhite(x)  (iswhite(x) && !isshared(x))
 
 #define changeage(o,f,t)  \
 	check_exp(getage(o) == (f), (o)->marked ^= ((f)^(t)))
@@ -167,15 +168,15 @@
 
 
 #define luaC_barrier(L,p,v) (  \
-	(iscollectable(v) && isblack(p) && iswhite(gcvalue(v)) && !isshared(gcvalue(v))) ?  \
+	(iscollectable(v) && isblack(p) && ispurewhite(gcvalue(v))) ?  \
 	luaC_barrier_(L,obj2gco(p),gcvalue(v)) : cast_void(0))
 
 #define luaC_barrierback(L,p,v) (  \
-	(iscollectable(v) && isblack(p) && iswhite(gcvalue(v)) && !isshared(gcvalue(v))) ? \
+	(iscollectable(v) && isblack(p) && ispurewhite(gcvalue(v))) ? \
 	luaC_barrierback_(L,p) : cast_void(0))
 
 #define luaC_objbarrier(L,p,o) (  \
-	(isblack(p) && iswhite(o) && !isshared(o)) ? \
+	(isblack(p) && ispurewhite(o)) ? \
 	luaC_barrier_(L,obj2gco(p),obj2gco(o)) : cast_void(0))
 
 LUAI_FUNC void luaC_fix (lua_State *L, GCObject *o);