diff --git a/polymer/eduke32/build/include/editor.h b/polymer/eduke32/build/include/editor.h
index d0978f980..e74ec38d2 100644
--- a/polymer/eduke32/build/include/editor.h
+++ b/polymer/eduke32/build/include/editor.h
@@ -116,6 +116,9 @@ int32_t yax_is121(int16_t bunchnum, int16_t getfloor);
 
 extern void M32_DrawRoomsAndMasks(void);
 
+extern void yax_tweakpicnums(int32_t bunchnum, int32_t cf, int32_t restore);  // editor-only
+extern void M32_ResetFakeRORTiles(void);
+
 extern int32_t kopen4loadfrommod(const char *filename, char searchfirst);
 
 // set to 1 to enable:
diff --git a/polymer/eduke32/build/src/build.c b/polymer/eduke32/build/src/build.c
index fd18d457e..9832b14d0 100644
--- a/polymer/eduke32/build/src/build.c
+++ b/polymer/eduke32/build/src/build.c
@@ -437,6 +437,25 @@ static void m32_keypresscallback(int32_t code, int32_t downp)
     VM_OnEvent(EVENT_KEYPRESS, -1);
 }
 
+void M32_ResetFakeRORTiles(void)
+{
+#ifdef POLYMER
+# ifdef YAX_ENABLE
+        // END_TWEAK ceiling/floor fake 'TROR' pics, see BEGIN_TWEAK in engine.c
+        if (rendmode==4 && showinvisibility)
+        {
+            int32_t i;
+
+            for (i=0; i<numyaxbunches; i++)
+            {
+                yax_tweakpicnums(i, YAX_CEILING, 1);
+                yax_tweakpicnums(i, YAX_FLOOR, 1);
+            }
+        }
+# endif
+#endif
+}
+
 void M32_DrawRoomsAndMasks(void)
 {
     yax_preparedrawrooms();
@@ -445,6 +464,7 @@ void M32_DrawRoomsAndMasks(void)
 
     ExtAnalyzeSprites();
     drawmasks();
+    M32_ResetFakeRORTiles();
 
 #ifdef POLYMER
     if (rendmode == 4 && searchit == 2)
@@ -453,6 +473,7 @@ void M32_DrawRoomsAndMasks(void)
         drawrooms(pos.x,pos.y,pos.z,ang,horiz,cursectnum);
         ExtAnalyzeSprites();
         drawmasks();
+        M32_ResetFakeRORTiles();
     }
 #endif
 }
diff --git a/polymer/eduke32/build/src/engine.c b/polymer/eduke32/build/src/engine.c
index b25f9d12a..6fb2639e8 100644
--- a/polymer/eduke32/build/src/engine.c
+++ b/polymer/eduke32/build/src/engine.c
@@ -694,13 +694,21 @@ static int yax_cmpbunches(const int16_t *b1, const int16_t *b2)
     return (bunchdist[*b2] - bunchdist[*b1]);
 }
 
-static void yax_tweakpicnums(int32_t bunchnum, int32_t cf, int32_t restore)
+
+void yax_tweakpicnums(int32_t bunchnum, int32_t cf, int32_t restore)
 {
     // for polymer, this is called before polymer_drawrooms() with restore==0
     // and after polymer_drawmasks() with restore==1
 
-    static int16_t opicnum[2][MAXSECTORS];
     int32_t i, dastat;
+    static int16_t opicnum[2][MAXSECTORS];
+#ifdef DEBUGGINGAIDS
+    static uint8_t expect_restore[2][YAX_MAXBUNCHES];
+
+    // must call this with restore == 0, 1,  0, 1,  0, 1,  ...
+    assert(expect_restore[cf][bunchnum] == restore);
+    expect_restore[cf][bunchnum] = !expect_restore[cf][bunchnum];
+#endif
 
     for (SECTORS_OF_BUNCH(bunchnum, cf, i))
     {
@@ -8091,7 +8099,7 @@ void drawrooms(int32_t daposx, int32_t daposy, int32_t daposz,
     if (rendmode == 4)
     {
 #  ifdef YAX_ENABLE
-        // BEGIN TWEAK ceiling/floor fake 'TROR' pics
+        // BEGIN_TWEAK ceiling/floor fake 'TROR' pics, see END_TWEAK in build.c
         if (editstatus && showinvisibility)
         {
             for (i=0; i<numyaxbunches; i++)
@@ -8577,17 +8585,6 @@ killsprite:
 #ifdef POLYMER
     if (rendmode == 4) {
         polymer_drawmasks();
-# ifdef YAX_ENABLE
-        // END TWEAK ceiling/floor fake 'TROR' pics
-        if (editstatus && showinvisibility)
-        {
-            for (i=0; i<numyaxbunches; i++)
-            {
-                yax_tweakpicnums(i, YAX_CEILING, 1);
-                yax_tweakpicnums(i, YAX_FLOOR, 1);
-            }
-        }
-# endif
     }
 #endif
 
diff --git a/polymer/eduke32/source/astub.c b/polymer/eduke32/source/astub.c
index bf59c79ae..989381035 100644
--- a/polymer/eduke32/source/astub.c
+++ b/polymer/eduke32/source/astub.c
@@ -2887,6 +2887,7 @@ static void ExtSE40Draw(int32_t spnum,int32_t x,int32_t y,int32_t z,int16_t a,in
     drawrooms(x+offx,y+offy,z+offz,a,h,sprite[floor2].sectnum);
     ExtAnalyzeSprites();
     drawmasks();
+    M32_ResetFakeRORTiles();
 
     if (draw_both)
     {
@@ -2912,6 +2913,7 @@ static void ExtSE40Draw(int32_t spnum,int32_t x,int32_t y,int32_t z,int16_t a,in
         drawrooms(x+offx,y+offy,z+offz,a,h,sprite[floor2].sectnum);
         ExtAnalyzeSprites();
         drawmasks();
+        M32_ResetFakeRORTiles();
     }
 
 } // end SE40