diff --git a/luprex/cpp/core/luastack.cpp b/luprex/cpp/core/luastack.cpp
index 6169dc91..c30b199f 100644
--- a/luprex/cpp/core/luastack.cpp
+++ b/luprex/cpp/core/luastack.cpp
@@ -94,10 +94,6 @@ lua_State *LuaCoreStack::newstate (lua_Alloc allocf) {
     lua_pushstring(L, "tangibles");
     lua_newtable(L);
     lua_rawset(L, LUA_REGISTRYINDEX);
-    lua_pushstring(L, "is_authoritative");
-    lua_pushboolean(L, 1);
-    lua_rawset(L, LUA_REGISTRYINDEX);
-
     return L;
 }
 
@@ -687,24 +683,6 @@ void LuaCoreStack::setvisited(LuaSlot tab, bool visited) const {
     lua_modflagbits(L_, tab.index(), 0x0010, visited ? 0x0010 : 0);
 }
 
-void LuaCoreStack::set_authoritative(bool auth) const {
-    lua_pushstring(L_, "is_authoritative");
-    lua_pushboolean(L_, auth ? 1 : 0);
-    lua_rawset(L_, LUA_REGISTRYINDEX);
-}
-
-void LuaCoreStack::guard_nopredict(const char *fn) {
-    if (lua_isyieldable(L_)) {
-        lua_pushstring(L_, "is_authoritative");
-        lua_rawget(L_, LUA_REGISTRYINDEX);
-        bool auth = lua_toboolean(L_, -1);
-        lua_pop(L_, 1);
-        if (!auth) {
-            lua_yield(L_, 0);
-            luaL_error(L_, "unexplained nopredict failure in %s", fn);
-        }
-    }
-}
 
 static int tailcall_continuation(lua_State *L)
 {
diff --git a/luprex/cpp/core/luastack.hpp b/luprex/cpp/core/luastack.hpp
index eb163f19..5b2a6db3 100644
--- a/luprex/cpp/core/luastack.hpp
+++ b/luprex/cpp/core/luastack.hpp
@@ -989,17 +989,6 @@ public:
     //
     void setvisited(LuaSlot tab, bool visited) const;
 
-    // Store whether the world is authoritative in the 
-    // registry.  This is used to implement guard_nopredict.
-    //
-    void set_authoritative(bool auth) const;
-
-    // Yield this thread with zero if in a nonauth model, and not a probe.
-    //
-    // The function name is just used for generating better error messages.
-    //
-    void guard_nopredict(const char *fn);
-
     // This is the largest integer that can be stored in a lua_Number.
     // In other words, any 53-bit number can be stored.
     //
diff --git a/luprex/cpp/core/world-core.cpp b/luprex/cpp/core/world-core.cpp
index 7ae96a43..1dfe4df6 100644
--- a/luprex/cpp/core/world-core.cpp
+++ b/luprex/cpp/core/world-core.cpp
@@ -131,8 +131,6 @@ World::World(WorldType wt) {
     LS.getglobaltable(globtab);
     LS.settabletype(globtab, LUA_TT_GLOBALENV);
 
-    // Store whether the world is authoritative in the registry.
-    LS.set_authoritative(wt == WORLD_TYPE_MASTER);
         
     // Create the globaldb in the registry.
     LS.rawset(LuaRegistry, "globaldb", LuaNewTable);
@@ -1002,14 +1000,12 @@ void World::guard_blockable(lua_State *L, const char *fn) {
 }
 
 void World::guard_nopredict(lua_State *L, const char *fn) {
-    // Caution: this code must be equivalent to the
-    // code in LuaCoreStack::guard_nopredict.
-    if (lthread_thread_id_ == 0) {
-        return;
-    }
     if (!is_authoritative()) {
-        lua_yield(L, 0);
-        luaL_error(L, "unexplained nopredict failure in %s", fn);
+        if (lthread_thread_id_ == 0) return;
+        if (lua_isyieldable(L)) {
+            lua_yield(L, 0);
+            luaL_error(L, "unexplained nopredict failure in %s", fn);
+        }
     }
 }