diff --git a/polymer/eduke32/build/include/build.h b/polymer/eduke32/build/include/build.h
index 2d8eb0ff2..3366b5bca 100644
--- a/polymer/eduke32/build/include/build.h
+++ b/polymer/eduke32/build/include/build.h
@@ -72,6 +72,8 @@ enum rendmode_t {
 #define MAXWALLSB ((MAXWALLS>>2)+(MAXWALLS>>3))
 
 #define MAXTILES 30720
+#define MAXUSERTILES (MAXTILES-16)  // reserve 16 tiles at the end
+
 #define MAXVOXELS 4096
 #define MAXSTATUS 1024
 #define MAXPLAYERS 16
diff --git a/polymer/eduke32/build/src/defs.c b/polymer/eduke32/build/src/defs.c
index 7914f4715..8ddb6a8cb 100644
--- a/polymer/eduke32/build/src/defs.c
+++ b/polymer/eduke32/build/src/defs.c
@@ -94,7 +94,7 @@ enum scripttoken_t
 };
 
 static int32_t lastmodelid = -1, lastvoxid = -1, modelskin = -1, lastmodelskin = -1, seenframe = 0;
-int32_t nextvoxid = 0;
+static int32_t nextvoxid = 0;
 
 #ifdef USE_OPENGL
 extern float alphahackarray[MAXTILES];
@@ -146,7 +146,7 @@ static int32_t check_tile_range(const char *defcmd, int32_t *tilebeg, int32_t *t
         swaplong(tilebeg, tileend);
     }
 
-    if ((unsigned)*tilebeg >= MAXTILES || (unsigned)*tileend >= MAXTILES)
+    if ((unsigned)*tilebeg >= MAXUSERTILES || (unsigned)*tileend >= MAXUSERTILES)
     {
         initprintf("Error: %s: Invalid tile range on line %s:%d\n", defcmd,
                    script->filename, scriptfile_getlinum(script,cmdtokptr));
@@ -159,7 +159,7 @@ static int32_t check_tile_range(const char *defcmd, int32_t *tilebeg, int32_t *t
 static int32_t check_tile(const char *defcmd, int32_t tile, const scriptfile *script,
                           const char *cmdtokptr)
 {
-    if ((unsigned)tile >= MAXTILES)
+    if ((unsigned)tile >= MAXUSERTILES)
     {
         initprintf("Error: %s: Invalid tile number on line %s:%d\n", defcmd,
                    script->filename, scriptfile_getlinum(script,cmdtokptr));
@@ -469,7 +469,7 @@ static int32_t defsparser(scriptfile *script)
             int32_t tile, tmp;
 
             if (scriptfile_getsymbol(script,&tile)) break;
-            if (tile >= MAXTILES)break;
+            if ((unsigned)tile >= MAXUSERTILES) break;
             if (scriptfile_getsymbol(script,&h_xsize[tile])) break;  // XXX
             if (scriptfile_getsymbol(script,&h_ysize[tile])) break;
             if (scriptfile_getsymbol(script,&tmp)) break;
@@ -585,7 +585,7 @@ static int32_t defsparser(scriptfile *script)
                 }
             }
 
-            if ((unsigned)tile >= MAXTILES)
+            if ((unsigned)tile >= MAXUSERTILES)
             {
                 initprintf("Error: missing or invalid 'tile number' for texture definition near line %s:%d\n",
                            script->filename, scriptfile_getlinum(script,texturetokptr));
@@ -1807,7 +1807,7 @@ static int32_t defsparser(scriptfile *script)
                         }
                     }
 
-                    if ((unsigned)tile >= MAXTILES) break;	// message is printed later
+                    if ((unsigned)tile >= MAXUSERTILES) break;	// message is printed later
                     if ((unsigned)pal >= MAXPALOOKUPS - RESERVEDPALS)
                     {
                         initprintf("Error: missing or invalid 'palette number' for texture definition near "
@@ -1886,7 +1886,7 @@ static int32_t defsparser(scriptfile *script)
                         }
                     }
 
-                    if ((unsigned)tile >= MAXTILES) break;	// message is printed later
+                    if ((unsigned)tile >= MAXUSERTILES) break;	// message is printed later
                     if (!fn)
                     {
                         initprintf("Error: missing 'file name' for texture definition near line %s:%d\n",
@@ -1923,7 +1923,7 @@ static int32_t defsparser(scriptfile *script)
                     break;
                 }
             }
-            if ((unsigned)tile >= MAXTILES)
+            if ((unsigned)tile >= MAXUSERTILES)
             {
                 initprintf("Error: missing or invalid 'tile number' for texture definition near line %s:%d\n",
                            script->filename, scriptfile_getlinum(script,texturetokptr));
@@ -2050,7 +2050,7 @@ static int32_t defsparser(scriptfile *script)
             if (scriptfile_getnumber(script,&e)) break;
 
             b = max(b, 0);
-            e = min(e, MAXTILES-1);
+            e = min(e, MAXUSERTILES-1);
 
             for (i=b; i<=e; i++)
                 picanm[i].sf |= (tokn==T_TEXHITSCANRANGE) ?
diff --git a/polymer/eduke32/build/src/engine.c b/polymer/eduke32/build/src/engine.c
index 233a24fa3..22417d0fe 100644
--- a/polymer/eduke32/build/src/engine.c
+++ b/polymer/eduke32/build/src/engine.c
@@ -11027,7 +11027,7 @@ int32_t loadpics(const char *filename, int32_t askedsize)
             kread(fil,&localtilestart,4); localtilestart = B_LITTLE32(localtilestart);
             kread(fil,&localtileend,4);   localtileend   = B_LITTLE32(localtileend);
 
-            if ((uint32_t)localtilestart >= MAXTILES || (uint32_t)localtileend >= MAXTILES)
+            if ((uint32_t)localtilestart >= MAXUSERTILES || (uint32_t)localtileend >= MAXUSERTILES)
             {
                 initprintf("loadpics: Invalid localtilestart or localtileend in %s\n", artfilename);
                 kclose(fil);
diff --git a/polymer/eduke32/source/duke3d.h b/polymer/eduke32/source/duke3d.h
index 4c0764756..8ecefd524 100644
--- a/polymer/eduke32/source/duke3d.h
+++ b/polymer/eduke32/source/duke3d.h
@@ -102,6 +102,7 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 #define TILE_TILT           (MAXTILES-2)
 #define TILE_ANIM           (MAXTILES-4)
 #define TILE_VIEWSCR        (MAXTILES-5)
+EDUKE32_STATIC_ASSERT(5 <= MAXTILES-MAXUSERTILES);
 
 // sprites with these statnums should be considered for fixing (bitmap)
 #define ROTFIXSPR_STATNUMP(k) ((k)==STAT_DEFAULT || (k)==STAT_STANDABLE || (k)==STAT_FX || \