diff --git a/polymer/eduke32/Makefile b/polymer/eduke32/Makefile
index d19844529..879d0043c 100644
--- a/polymer/eduke32/Makefile
+++ b/polymer/eduke32/Makefile
@@ -158,12 +158,13 @@ ifneq (0,$(DISABLEINLINING))
 endif
 
 MISCGAMEDEPS=
+MISCEDITORDEPS=
 
 
 ## Lunatic devel
 ifneq (0,$(LUNATIC))
-    EDITOROBJS+= $(OBJ)/lunatic_m32.$o
-    GAMEOBJS+= $(OBJ)/lunatic_game.$o
+    EDITOROBJS+= $(OBJ)/lunatic_m32.$o $(OBJ)/luaJIT_BC_defs_common.$o
+    GAMEOBJS+= $(OBJ)/lunatic_game.$o $(OBJ)/luaJIT_BC_defs_common.$o
 
     GAMEOBJS+= $(OBJ)/../lpeg.$o  # TEMP
     GAMEOBJS+= $(OBJ)/luaJIT_BC_con_lang.$o \
@@ -188,7 +189,9 @@ ifneq (0,$(LUNATIC))
     endif
     ifeq ($(PLATFORM),WINDOWS)
         MISCGAMEDEPS+= $(SRC)/lunatic/eduke32.def
-        PRINTLDFLAGS+= $(SRC)/lunatic/eduke32.def
+        GAMELDFLAGS+= $(SRC)/lunatic/eduke32.def
+        MISCEDITORDEPS+= $(SRC)/lunatic/mapster32.def
+        EDITORLDFLAGS+= $(SRC)/lunatic/mapster32.def
     endif
     ifeq ($(PLATFORM),LINUX)
         GAMELDFLAGS+= -Wl,--dynamic-list=$(SRC)/lunatic/dynsymlist
@@ -366,7 +369,7 @@ ifeq ($(PLATFORM),DARWIN)
 	cp -f "$(EDUKE32)" "EDuke32.app/Contents/MacOS/"
 endif
 
-$(MAPSTER32): $(EDITOROBJS) $(EOBJ)/$(ENGINELIB) $(EOBJ)/$(EDITORLIB) $(JAUDIOLIBDIR)/$(JAUDIOLIB)
+$(MAPSTER32): $(EDITOROBJS) $(EOBJ)/$(ENGINELIB) $(EOBJ)/$(EDITORLIB) $(JAUDIOLIBDIR)/$(JAUDIOLIB) $(MISCEDITORDEPS)
 	$(LINK_STATUS)
 	if $(LINKER) -o $@ $^ $(OURLDFLAGS) $(EDITORLDFLAGS) $(OURLIBS) $(STATICSTDCPP) $(STDCPPLIB); then $(LINK_OK); else $(LINK_FAILED); fi
 ifeq (1,$(RELEASE))	
@@ -465,12 +468,15 @@ $(SRC)/lunatic/dynsymlist_osx: $(SRC)/lunatic/dynsymlist
 #$(SRC)/lunatic/aliases_list: $(SRC)/lunatic/dynsymlist_osx
 #	sed 's/_\([A-Za-z_][A-Za-z_0-9]*\)/_\1 \1/g' $< > $@
 
-# TODO: _m32
 # List of exported symbols, Windows
 $(SRC)/lunatic/eduke32.def: $(SRC)/lunatic/dynsymlist
 	echo EXPORTS > $@
 	sed 's/[{};]//g' $< >> $@
 
+$(SRC)/lunatic/mapster32.def: $(SRC)/lunatic/dynsymlist_m32
+	echo EXPORTS > $@
+	sed 's/[{};]//g' $< >> $@
+
 ####
 
 $(OBJ)/%.$o: Apple/%.m
diff --git a/polymer/eduke32/source/lunatic/defs.ilua b/polymer/eduke32/source/lunatic/defs.ilua
index a0d60c0dd..4014c2515 100644
--- a/polymer/eduke32/source/lunatic/defs.ilua
+++ b/polymer/eduke32/source/lunatic/defs.ilua
@@ -42,7 +42,7 @@ end
 
 -- load them!
 local defs_c = require("defs_common")
-
+local strip_const = defs_c.strip_const
 
 ---=== EDuke32 game definitions ===---
 
@@ -222,11 +222,6 @@ local DUKEPLAYER_STRUCT = [[
 local randgen = require("randgen")
 local geom = require("geom")
 
--- Converts a template struct definition to an internal, unrestricted one.
-local function strip_const(structstr)
-    return string.gsub(structstr, "const ", "");
-end
-
 local ma_rand = randgen.new(true)  -- initialize to "random" (time-based) seed
 local ma_count = nil
 
diff --git a/polymer/eduke32/source/lunatic/defs_common.lua b/polymer/eduke32/source/lunatic/defs_common.lua
index d17e28d6d..ea56304fc 100644
--- a/polymer/eduke32/source/lunatic/defs_common.lua
+++ b/polymer/eduke32/source/lunatic/defs_common.lua
@@ -6,6 +6,8 @@
 local ffi = require("ffi")
 local ffiC = ffi.C
 
+local string = require("string")
+
 local error = error
 local pairs = pairs
 local setmetatable = setmetatable
@@ -20,19 +22,41 @@ module(...)
 
 
 --== Core engine structs ==--
+local SPRITE_STRUCT = [[
+{
+    int32_t x, y, z;
+    uint16_t cstat;
+    const int16_t picnum;
+    int8_t shade;
+    uint8_t pal, clipdist, filler;
+    uint8_t xrepeat, yrepeat;
+    int8_t xoffset, yoffset;
+    const int16_t sectnum, statnum;
+    int16_t ang, owner, xvel, yvel, zvel;
+    int16_t lotag, hitag, extra;
+}
+]]
+
+-- Converts a template struct definition to an internal, unrestricted one.
+function strip_const(structstr)
+    return string.gsub(structstr, "const ", "");
+end
+
 
 -- TODO: provide getters for unsigned {hi,lo}tag?
-ffi.cdef[[
+ffi.cdef([[
 #pragma pack(push,1)
 typedef struct
 {
     const int16_t wallptr, wallnum;
     int32_t ceilingz, floorz;
     uint16_t ceilingstat, floorstat;
-    int16_t ceilingpicnum, ceilingheinum;
+    const int16_t ceilingpicnum;
+    int16_t ceilingheinum;
     int8_t ceilingshade;
     uint8_t ceilingpal, ceilingxpanning, ceilingypanning;
-    int16_t floorpicnum, floorheinum;
+    const int16_t floorpicnum;
+    int16_t floorheinum;
     int8_t floorshade;
     uint8_t floorpal, floorxpanning, floorypanning;
     uint8_t visibility, filler;
@@ -44,25 +68,19 @@ typedef struct
     int32_t x, y;
     const int16_t point2, nextwall, nextsector;
     uint16_t cstat;
-    int16_t picnum, overpicnum;
+    const int16_t picnum, overpicnum;
     int8_t shade;
     uint8_t pal, xrepeat, yrepeat, xpanning, ypanning;
     int16_t lotag, hitag, extra;
 } walltype;
 
 typedef struct
-{
-    int32_t x, y, z;
-    uint16_t cstat;
-    int16_t picnum;
-    int8_t shade;
-    uint8_t pal, clipdist, filler;
-    uint8_t xrepeat, yrepeat;
-    int8_t xoffset, yoffset;
-    const int16_t sectnum, statnum;
-    int16_t ang, owner, xvel, yvel, zvel;
-    int16_t lotag, hitag, extra;
-} spritetype;
+]].. SPRITE_STRUCT ..[[
+spritetype;
+
+typedef struct
+]].. strip_const(SPRITE_STRUCT) ..[[
+spritetype_u_t;
 
 typedef struct {
     const uint32_t mdanimtims;
@@ -90,7 +108,7 @@ typedef struct {
     char r,g,b,f;
 } palette_t;
 #pragma pack(pop)
-]]
+]])
 
 local vec3_ct = ffi.typeof("vec3_t")
 local hitdata_ct = ffi.typeof("hitdata_t")
@@ -198,6 +216,21 @@ int32_t ksqrt(uint32_t num);
 ]]
 
 
+local spritetype_ptr_ct = ffi.typeof("spritetype_u_t *")
+
+local spritetype_mt = {
+    __index = {
+        set_picnum = function(s, tilenum)
+            if (tilenum >= ffiC.MAXTILES+0ULL) then
+                error("attempt to set invalid picnum "..tilenum, 2)
+            end
+            ffi.cast(spritetype_ptr_ct, s).picnum = tilenum
+        end
+    },
+}
+ffi.metatype("spritetype", spritetype_mt)
+
+
 ---=== Restricted access to C variables from Lunatic ===---
 
 -- set metatable and forbid setting it further
@@ -209,18 +242,18 @@ end
 ---- indirect C array access ----
 local sector_mt = {
     __index = function(tab, key)
-                  if (key >= 0 and key < ffiC.numsectors) then return ffiC.sector[key] end
-                  error('out-of-bounds sector[] read access', 2)
-              end,
+        if (key >= 0 and key < ffiC.numsectors) then return ffiC.sector[key] end
+        error('out-of-bounds sector[] read access', 2)
+    end,
 
     __newindex = function(tab, key, val) error('cannot write directly to sector[] struct', 2) end,
 }
 
 local wall_mt = {
     __index = function(tab, key)
-                  if (key >= 0 and key < ffiC.numwalls) then return ffiC.wall[key] end
-                  error('out-of-bounds wall[] read access', 2)
-              end,
+        if (key >= 0 and key < ffiC.numwalls) then return ffiC.wall[key] end
+        error('out-of-bounds wall[] read access', 2)
+    end,
 
     __newindex = function(tab, key, val) error('cannot write directly to wall[] struct', 2) end,
 }
@@ -230,14 +263,14 @@ function creategtab(ctab, maxidx, name)
     local tab = {}
     local tmpmt = {
         __index = function(tab, key)
-                      if (key>=0 and key < maxidx) then
-                          return ctab[key]
-                      end
-                      error('out-of-bounds '..name..' read access', 2)
-                  end,
+            if (key>=0 and key < maxidx) then
+                return ctab[key]
+            end
+            error('out-of-bounds '..name..' read access', 2)
+        end,
         __newindex = function(tab, key, val)
-                         error('cannot write directly to '..name, 2)
-                     end,
+            error('cannot write directly to '..name, 2)
+        end,
     }
 
     return setmtonce(tab, tmpmt)
diff --git a/polymer/eduke32/source/lunatic/lunacon.lua b/polymer/eduke32/source/lunatic/lunacon.lua
index abd8a3311..ed1324acd 100644
--- a/polymer/eduke32/source/lunatic/lunacon.lua
+++ b/polymer/eduke32/source/lunatic/lunacon.lua
@@ -761,7 +761,7 @@ local Ci = {
         / ACS":set_move(%1)",
 
     cactor = cmd(D)
-        / SPS".picnum=%1",  -- TODO: wrap, e.g. sprite[]:set_picnum(tilenum), bound check there
+        / SPS":set_picnum(%1)",
     count = cmd(D)
         / ACS":set_count(%1)",
     cstator = cmd(D),
diff --git a/polymer/eduke32/source/lunatic/test.elua b/polymer/eduke32/source/lunatic/test.elua
index a18834d0b..0c5fd133f 100644
--- a/polymer/eduke32/source/lunatic/test.elua
+++ b/polymer/eduke32/source/lunatic/test.elua
@@ -182,6 +182,7 @@ checkfail("do local bt=require'bittest'; bt.QWE=1; end", "modifying module table
 -- the cdata returned by player[] can't be made into a pointer!
 checkfail("do local pl=player[0]; i=pl[1]; end")
 checkfail("do local ud=gv.ud.camera; end", "dummy variable: read access forbidden")  -- test for proper decl()
+checkfail("sprite[0]:set_picnum(-10)", "attempt to set invalid picnum")
 
 printf('ceilingbunch of sector 0: %d', getbunch(0, gv.CEILING))