diff --git a/3rd/lua/lgc.c b/3rd/lua/lgc.c
index 235ee896..6370db74 100644
--- a/3rd/lua/lgc.c
+++ b/3rd/lua/lgc.c
@@ -65,7 +65,7 @@
 */
 #define maskcolors	(~(bitmask(BLACKBIT) | WHITEBITS))
 #define makewhite(g,x)	\
- (x->marked = cast_byte((x->marked & maskcolors) | luaC_white(g)))
+ (x->marked = cast_byte((x->marked & maskcolors) | (x->marked & bitmask(SHAREBIT)) | luaC_white(g)))
 
 #define white2gray(x)	resetbits(x->marked, WHITEBITS)
 #define black2gray(x)	resetbit(x->marked, BLACKBIT)
@@ -756,7 +756,7 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
       freeobj(L, curr);  /* erase 'curr' */
     }
     else {  /* change mark to 'white' */
-      curr->marked = cast_byte((marked & maskcolors) | white);
+      curr->marked = cast_byte((marked & maskcolors) | (marked & bitmask(SHAREBIT)) |white);
       p = &curr->next;  /* go to next element */
     }
   }