diff --git a/luprex/cpp/core/luasnap.cpp b/luprex/cpp/core/luasnap.cpp
index 8505b4d5..1dfc3dd5 100644
--- a/luprex/cpp/core/luasnap.cpp
+++ b/luprex/cpp/core/luasnap.cpp
@@ -33,10 +33,17 @@ void LuaSnap::serialize(StreamBuffer *sb) {
     // Lua stack should be empty.
     assert(lua_gettop(state_) == 0);
 
-    // lua variables that we'll need.
-    LuaVar key, value;
-    LuaRet permstable, regcopy;
-    LuaDefStack LS(state_, permstable, regcopy, key, value);
+    // We'll allocate stack slots manually, to ensure
+    // that the thread serializes as we expect it to.
+    lua_pushnil(state_); // permstable
+    lua_pushnil(state_); // regcopy
+    lua_pushnil(state_); // key
+    lua_pushnil(state_); // value
+    LuaSpecial permstable(1);
+    LuaSpecial regcopy(2);
+    LuaSpecial key(3);
+    LuaSpecial value(4);
+    LuaCoreStack LS(state_);
 
     // Construct a copy of the registry table.
     LS.set(regcopy, LuaNewTable);
@@ -62,10 +69,8 @@ void LuaSnap::serialize(StreamBuffer *sb) {
     LS.rawget(permstable, LuaRegistry, "persist");
     assert(LS.istable(permstable));
 
-    // When we call 'LS.result', this should leave the
-    // permstable and the regcopy on the stack.
-    LS.result();
-    assert(lua_gettop(state_) == 2);
+    // Remove key and value from stack, leaving permstable and regcopy.
+    lua_settop(state_, 2);
 
     // Write dummy length, use eris to write data, then overwrite length.
     sb->write_int64(0);
@@ -88,13 +93,17 @@ void LuaSnap::deserialize(StreamBuffer *sb) {
     lua_pushstring(state_, "unpersist");
     lua_rawget(state_, LUA_REGISTRYINDEX);
     eris_undump(state_, sb->lua_reader, ud);
+
+    // Set up a stack frame manually.  Eris deserialization
+    // should have left permstable and regcopy on the stack.
     assert(lua_gettop(state_) == 2);
-
-    // Set up a stack frame.
-    LuaArg permstable, regcopy;
-    LuaVar key, value;
-    LuaDefStack LS(state_, permstable, regcopy, key, value);
-
+    LuaSpecial permstable(1);
+    LuaSpecial regcopy(2);
+    lua_pushnil(state_);
+    lua_pushnil(state_);
+    LuaSpecial key(3);
+    LuaSpecial value(4);
+    LuaCoreStack LS(state_);
     assert(LS.istable(regcopy));
 
     // Copy the contents of the snapshot over to the registry.
@@ -102,8 +111,7 @@ void LuaSnap::deserialize(StreamBuffer *sb) {
     while (LS.next(regcopy, key, value) != 0) {
         LS.rawset(LuaRegistry, key, value);
     }
-    LS.result();
-    assert(lua_gettop(state_) == 0);
+    lua_settop(state_, 0);
 }
 
 // Snapshot and rollback can trivially be implemented on top of serialize and
diff --git a/luprex/cpp/core/luastack.hpp b/luprex/cpp/core/luastack.hpp
index 6edbc988..1d9dda3a 100644
--- a/luprex/cpp/core/luastack.hpp
+++ b/luprex/cpp/core/luastack.hpp
@@ -156,16 +156,18 @@
 class LuaSlot : public eng::nevernew {
 protected:
     int index_;
+
+    constexpr LuaSlot(int n) : index_(n) {}
+
 private:
     inline operator int() const {
         return index_;
     }
-public:
-    LuaSlot() {
-        index_ = 0;
-    }
 
-    int index() const {
+public:
+    constexpr LuaSlot() : index_(0) {}
+
+    inline int index() const {
         return index_;
     }
     
@@ -181,20 +183,30 @@ class LuaVar : public LuaSlot {};
 
 class LuaSpecial : public LuaSlot {
 public:
-    LuaSpecial(int n) {
-        index_ = n;
-    }
+    constexpr LuaSpecial(int n) : LuaSlot(n) {}
 };
 
 extern LuaSpecial LuaRegistry;
 
-class LuaUpvalue : public LuaSlot {
-    public:
-        LuaUpvalue(int n) {
-            index_ = lua_upvalueindex(n);
-        }
+class LuaExtraArgs {
+private:
+    int index_; 
+    int size_;
+
+public:
+    LuaExtraArgs() {
+        index_ = 0;
+        size_ = 0;
+    }
+
+    LuaSpecial operator[] (int n) const { return LuaSpecial(index_ + n); }
+    int size() const { return size_; }
+
+    friend class LuaCoreStack;
+    friend class LuaDefStack;
 };
 
+
 class LuaNilMarker {};
 extern LuaNilMarker LuaNil;
 
@@ -283,27 +295,33 @@ protected:
         int nret;
         int narg;
         int nvar;
-        constexpr Counts(int r, int a, int v) : nret(r), narg(a), nvar(v) {}
+        int nextra;
+        constexpr Counts(int nr, int na, int nv, int ne) : nret(nr), narg(na), nvar(nv), nextra(ne) {}
     };
 
-    template<int NRET, int NARG, int NVAR, class... SS>
+    template<int NRET, int NARG, int NVAR, int NEXTRA, class... SS>
     constexpr static Counts count_slots(LuaRet &v, SS & ... stackslots)
     {
-        return count_slots<NRET+1, NARG, NVAR>(stackslots...);
+        return count_slots<NRET+1, NARG, NVAR, NEXTRA>(stackslots...);
     }
-    template<int NRET, int NARG, int NVAR, class... SS>
+    template<int NRET, int NARG, int NVAR, int NEXTRA, class... SS>
     constexpr static Counts count_slots(LuaArg &v, SS & ... stackslots)
     {
-        return count_slots<NRET, NARG+1, NVAR>(stackslots...);
+        return count_slots<NRET, NARG+1, NVAR, NEXTRA>(stackslots...);
     }
-    template<int NRET, int NARG, int NVAR, class... SS>
+    template<int NRET, int NARG, int NVAR, int NEXTRA, class... SS>
     constexpr static Counts count_slots(LuaVar &v, SS & ... stackslots)
     {
-        return count_slots<NRET, NARG, NVAR+1>(stackslots...);
+        return count_slots<NRET, NARG, NVAR+1, NEXTRA>(stackslots...);
     }
-    template<int NRET, int NARG, int NVAR>
+    template<int NRET, int NARG, int NVAR, int NEXTRA, class... SS>
+    constexpr static Counts count_slots(LuaExtraArgs &v, SS & ... stackslots)
+    {
+        return count_slots<NRET, NARG, NVAR, NEXTRA+1>(stackslots...);
+    }
+    template<int NRET, int NARG, int NVAR, int NEXTRA>
     constexpr static Counts count_slots() {
-        return Counts(NRET, NARG, NVAR);
+        return Counts(NRET, NARG, NVAR, NEXTRA);
     }
 
 private:
@@ -649,47 +667,76 @@ public:
 
 class LuaDefStack : public LuaCoreStack {
 private:
+    int top_;
     int nret_;
 
-    template<int RETP, int ARGP, int VARP, class... SS>
+    template<int RETP, int ARGP, int VARP, int EXTRAP, int EXTRAC, class... SS>
     void assign_slots(LuaRet &v, SS & ... stackslots) {
         v.index_ = RETP;
-        assign_slots<RETP+1, ARGP, VARP>(stackslots...);
+        assign_slots<RETP+1, ARGP, VARP, EXTRAP, EXTRAC>(stackslots...);
     }
-    template<int RETP, int ARGP, int VARP, class... SS>
+    template<int RETP, int ARGP, int VARP, int EXTRAP, int EXTRAC, class... SS>
     void assign_slots(LuaArg &v, SS & ... stackslots) {
         v.index_ = ARGP;
-        assign_slots<RETP, ARGP+1, VARP>(stackslots...);
+        assign_slots<RETP, ARGP+1, VARP, EXTRAP, EXTRAC>(stackslots...);
     }
-    template<int RETP, int ARGP, int VARP, class... SS>
+    template<int RETP, int ARGP, int VARP, int EXTRAP, int EXTRAC, class... SS>
     void assign_slots(LuaVar &v, SS & ... stackslots) {
         v.index_ = VARP;
-        assign_slots<RETP, ARGP, VARP+1>(stackslots...);
+        assign_slots<RETP, ARGP, VARP+1, EXTRAP, EXTRAC>(stackslots...);
     }
-    template<int NRET, int NARG, int NVAR>
+    template<int RETP, int ARGP, int VARP, int EXTRAP, int EXTRAC, class... SS>
+    void assign_slots(LuaExtraArgs &v, SS & ... stackslots) {
+        v.index_ = EXTRAP;
+        v.size_ = EXTRAC;
+        assign_slots<RETP, ARGP, VARP, EXTRAP, EXTRAC>(stackslots...);
+    }
+    template<int RETP, int ARGP, int VARP, int EXTRAP, int EXTRAC>
     void assign_slots() {}
 
+    template<class... SS>
+    void vassign_slots(int retp, int argp, int varp, int extrap, int extrac, LuaRet &v, SS & ... stackslots) {
+        v.index_ = retp;
+        vassign_slots(retp+1, argp, varp, extrap, extrac, stackslots...);
+    }
+    template<class... SS>
+    void vassign_slots(int retp, int argp, int varp, int extrap, int extrac, LuaArg &v, SS & ... stackslots) {
+        v.index_ = argp;
+        vassign_slots(retp, argp+1, varp, extrap, extrac, stackslots...);
+    }
+    template<class... SS>
+    void vassign_slots(int retp, int argp, int varp, int extrap, int extrac, LuaVar &v, SS & ... stackslots) {
+        v.index_ = varp;
+        vassign_slots(retp, argp, varp+1, extrap, extrac, stackslots...);
+    }
+    template<class... SS>
+    void vassign_slots(int retp, int argp, int varp, int extrap, int extrac, LuaExtraArgs &v, SS & ... stackslots) {
+        v.index_ = extrap;
+        v.size_ = extrac;
+        vassign_slots(retp, argp, varp, extrap, extrac, stackslots...);
+    }
+    void vassign_slots(int retp, int argp, int varp, int extrap, int extrac) {}
+
+
 public:
     template<class... SS>
     inline LuaDefStack(lua_State *L, SS & ... stackslots) : LuaCoreStack(L) {
-        constexpr Counts counts = count_slots<0, 0, 0>(stackslots...);
-        if (lua_gettop(L_) != counts.narg) {
-            luaL_error(L_, "function expects exactly %d arguments", counts.narg);
+        constexpr Counts counts = count_slots<0, 0, 0, 0>(stackslots...);
+        if (lua_gettop(L_) < counts.narg) {
+            luaL_error(L_, "function expects at least %d arguments", counts.narg);
         }
-        lua_checkstack(L, counts.narg + counts.nvar + counts.nret + 20);
-        for (int i = 0; i < counts.nret; i ++) {
-            lua_pushnil(L_);
-            lua_insert(L_, i + 1);
-        }
-        for (int i = 0; i < counts.nvar; i++) {
+        lua_checkstack(L, counts.nvar + counts.nret + 20);
+        int top = lua_gettop(L);
+        for (int i = 0; i < counts.nvar + counts.nret; i ++) {
             lua_pushnil(L_);
         }
-        assign_slots<1, 1 + counts.nret, 1 + counts.nret + counts.narg>(stackslots...);
+        vassign_slots(1 + counts.nvar + top, 1, 1 + top, 1 + counts.narg, top - counts.narg, stackslots...);
+        top_ = top + counts.nvar + counts.nret;
         nret_ = counts.nret;
     }
 
     int result() {
-        lua_settop(L_, nret_);
+        lua_settop(L_, top_);
         return nret_;
     }
 
@@ -730,9 +777,10 @@ private:
 public:
     template<class... SS>
     LuaExtStack(lua_State *L, SS & ... stackslots) : LuaCoreStack(L) {
-        constexpr Counts counts = count_slots<0, 0, 0>(stackslots...);
+        constexpr Counts counts = count_slots<0, 0, 0, 0>(stackslots...);
         static_assert(counts.narg == 0, "LuaExtStack doesn't allow LuaArg parameters");
         static_assert(counts.nret == 0, "LuaExtStack doesn't allow LuaRet parameters");
+        static_assert(counts.nextra == 0, "LuaExtStack doesn't allow LuaExtraArgs parameters");
         lua_checkstack(L_, counts.nvar + 20);
         oldtop_ = lua_gettop(L_);
         for (int i = 0; i < counts.nvar; i++) {
diff --git a/luprex/cpp/core/pprint.cpp b/luprex/cpp/core/pprint.cpp
index 2180633c..a786d766 100644
--- a/luprex/cpp/core/pprint.cpp
+++ b/luprex/cpp/core/pprint.cpp
@@ -270,19 +270,17 @@ LuaDefine(string_pprint, "obj1, obj2, ...",
     "|start at indentation level zero, and always expand the"
     "|top-level table."
     "|") {
-    int n = lua_gettop(L);
-    LuaCoreStack LS(L);
+    LuaRet result;
+    LuaExtraArgs extra;
+    LuaDefStack LS(L, result, extra);
+
     util::ostringstream oss;
-    for (int i = 1; i <= n; i++) {
-        LuaSpecial root(i);
-        pprint(LS, root, PrettyPrintOptions(), &oss);
-        if (i < n) oss << "\n";
+    for (int i = 0; i < extra.size(); i++) {
+        pprint(LS, extra[i], PrettyPrintOptions(), &oss);
+        oss << "\n";
     }
-    oss << std::endl;
-    lua_settop(L, 1);
-    LuaSpecial result(1);
     LS.set(result, oss.view());
-    return 1;
+    return LS.result();
 }
 
 LuaDefine(string_pprintx, "options",
diff --git a/luprex/cpp/core/world-accessor.cpp b/luprex/cpp/core/world-accessor.cpp
index aa3a7407..d447b2c9 100644
--- a/luprex/cpp/core/world-accessor.cpp
+++ b/luprex/cpp/core/world-accessor.cpp
@@ -728,14 +728,12 @@ LuaDefine(pprint, "obj1, obj2, ...",
     "|") {
     World *w = World::fetch_global_pointer(L);
     std::ostream *ostream = w->lthread_print_stream();
-    int n = lua_gettop(L);
-    LuaDefStack LS(L);
-    for (int i = 1; i <= n; i++) {
-        LuaSpecial root(i);
-        pprint(LS, root, PrettyPrintOptions(), ostream);
-        if (i < n) (*ostream) << "\n";
+    LuaExtraArgs extra;
+    LuaDefStack LS(L, extra);
+    for (int i = 0; i < extra.size(); i++) {
+        pprint(LS, extra[i], PrettyPrintOptions(), ostream);
+        (*ostream) << std::endl;
     }
-    (*ostream) << std::endl;
     return LS.result();
 
 }