diff --git a/VM/src/lgc.cpp b/VM/src/lgc.cpp
index 690536d0..6e8dfd20 100644
--- a/VM/src/lgc.cpp
+++ b/VM/src/lgc.cpp
@@ -232,9 +232,9 @@ static LuaNode* relink(GCObject* o, LuaNode* n, LuaNode* list) {
     gkey(n)->extra[0] = static_cast<int>(static_cast<uint32_t>(intptr & 0xFFFFFFFF));
     // Save the link to the next worklist entry in the key extra slot and value tt slot.
     // Note: The value tt is saved in the key tt which can be restored from the key GCObject.
-    if (sizeof(uintptr_t) > 4) {
+    if /* constexpr */ (sizeof(uintptr_t) > 4) {
         LUAU_ASSERT(sizeof(uintptr_t) <= 8);
-        gval(n)->tt = static_cast<int>(static_cast<uint32_t>(intptr >> 32));
+        gval(n)->tt = static_cast<int>(static_cast<uint32_t>(static_cast<uint64_t>(intptr) >> 32));
     }
     return n;
 }
@@ -273,8 +273,8 @@ static LuaNode* nextandrestore(LuaNode* n) {
     uintptr_t intptr = static_cast<uint32_t>(gkey(n)->extra[0]);
     // Rebuild ptr to next element in the worklist which is stored in the key extra value
     // and the tt slot of the value.
-    if (sizeof(uintptr_t) > 4) {
-        intptr |= static_cast<uintptr_t>(static_cast<uint32_t>(gval(n)->tt)) << 32;
+    if /* constexpr */ (sizeof(uintptr_t) > 4) {
+        intptr |= static_cast<uintptr_t>(static_cast<uint64_t>(static_cast<uint32_t>(gval(n)->tt)) << 32);
     }
     ttype(gval(n)) = ttype(gkey(n)); // Value tt is saved in the key tt.
     ttype(gkey(n)) = gcvalue(gkey(n))->gch.tt; // Key tt can be restored from the key gc value.
diff --git a/tests/conformance/gc.lua b/tests/conformance/gc.lua
index 5804ea7f..902296a5 100644
--- a/tests/conformance/gc.lua
+++ b/tests/conformance/gc.lua
@@ -132,14 +132,14 @@ print('weak tables')
 a = {}; setmetatable(a, {__mode = 'k'});
 -- fill a with some `collectable' indices
 for i=1,lim do a[{}] = i end
--- and some non-collectable ones
 for i=1,lim do local t={}; a[t]=t end
+-- and some non-collectable ones
 for i=1,lim do a[i] = i end
 for i=1,lim do local s=string.rep('@', i); a[s] = s..'#' end
 collectgarbage()
 local i = 0
 for k,v in pairs(a) do assert(k==v or k..'#'==v); i=i+1 end
-assert(i == 3*lim)
+assert(i == 2*lim)
 
 a = {}; setmetatable(a, {__mode = 'v'});
 a[1] = string.rep('b', 21)