diff --git a/source/build/include/build.h b/source/build/include/build.h
index 20e66691e..ae1291e69 100644
--- a/source/build/include/build.h
+++ b/source/build/include/build.h
@@ -365,7 +365,11 @@ typedef struct {
 #define SPREXT_TSPRACCESS 16
 #define SPREXT_TEMPINVISIBLE 32
 
-#define TSPR_EXTRA_MDHACK 1
+// using the clipdist field
+enum
+{
+    TSPR_FLAGS_MDHACK = 1u<<0u,
+};
 
 EXTERN int32_t guniqhudid;
 EXTERN int32_t spritesortcnt;
diff --git a/source/build/src/mdsprite.cpp b/source/build/src/mdsprite.cpp
index 9f28372f8..cd53e356b 100644
--- a/source/build/src/mdsprite.cpp
+++ b/source/build/src/mdsprite.cpp
@@ -1584,11 +1584,11 @@ static int32_t polymost_md3draw(md3model_t *m, tspriteptr_t tspr)
     if (grhalfxdown10x < 0) { mat[0] = -mat[0]; mat[4] = -mat[4]; mat[8] = -mat[8]; mat[12] = -mat[12]; }
 
     //------------
-    // TSPR_EXTRA_MDHACK is an ugly hack in game.c:G_DoSpriteAnimations() telling md2sprite
+    // TSPR_FLAGS_MDHACK is an ugly hack in game.c:G_DoSpriteAnimations() telling md2sprite
     // to use Z-buffer hacks to hide overdraw problems with the flat-tsprite-on-floor shadows,
     // also disabling detail, glow, normal, and specular maps.
 
-    if (tspr->extra&TSPR_EXTRA_MDHACK)
+    if (tspr->clipdist & TSPR_FLAGS_MDHACK)
     {
         double f = (double) (tspr->owner + 1) * (std::numeric_limits<double>::epsilon() * 8.0);
         if (f != 0.0) f *= 1.0/(double) (sepldist(globalposx - tspr->x, globalposy - tspr->y)>>5);
@@ -1640,7 +1640,7 @@ static int32_t polymost_md3draw(md3model_t *m, tspriteptr_t tspr)
         if (sext->offset.y)  // Compare with SCREEN_FACTORS above
             a0.y = (float) sext->offset.y * f;
 
-        if ((sext->offset.z) && !(tspr->extra&TSPR_EXTRA_MDHACK))  // Compare with SCREEN_FACTORS above
+        if ((sext->offset.z) && !(tspr->clipdist & TSPR_FLAGS_MDHACK))  // Compare with SCREEN_FACTORS above
             a0.z = (float)sext->offset.z / (gxyaspect * fxdimen * (65536.f/128.f) * (m0.z+m1.z));
 
         k0 = (float)sintable[(sext->pitch+512)&2047] * (1.f/16384.f);
@@ -1720,7 +1720,7 @@ static int32_t polymost_md3draw(md3model_t *m, tspriteptr_t tspr)
 		float detscale = 1.f;
 
 		// The data lookup here is one incredible mess. Thanks to whoever cooked this up... :(
-        if (!(tspr->extra&TSPR_EXTRA_MDHACK))
+        if (!(tspr->clipdist & TSPR_FLAGS_MDHACK))
         {
 			det = tex = hw_detailmapping ? mdloadskin((md2model_t *) m, tile2model[Ptile2tile(tspr->picnum, lpal)].skinnum, DETAILPAL, surfi, nullptr) : nullptr;
 			if (det)
diff --git a/source/build/src/voxmodel.cpp b/source/build/src/voxmodel.cpp
index 8421d9947..7d666a214 100644
--- a/source/build/src/voxmodel.cpp
+++ b/source/build/src/voxmodel.cpp
@@ -1051,7 +1051,7 @@ int32_t polymost_voxdraw(voxmodel_t *m, tspriteptr_t const tspr)
     f = (65536.f*512.f) / ((float)xdimen*viewingrange);
     g = 32.f / ((float)xdimen*gxyaspect);
 
-    int const shadowHack = !!(tspr->extra&TSPR_EXTRA_MDHACK);
+    int const shadowHack = !!(tspr->clipdist & TSPR_FLAGS_MDHACK);
 
     m0.y *= f; a0.y = (((float)(tspr->x-globalposx)) * (1.f/1024.f) + a0.y) * f;
     m0.x *=-f; a0.x = (((float)(tspr->y-globalposy)) * -(1.f/1024.f) + a0.x) * -f;
diff --git a/source/duke3d/src/game.cpp b/source/duke3d/src/game.cpp
index b11adc092..c874077cc 100644
--- a/source/duke3d/src/game.cpp
+++ b/source/duke3d/src/game.cpp
@@ -4168,7 +4168,7 @@ skip:
                                 tsprShadow->yrepeat = 0;
                                 // 512:trans reverse
                                 //1024:tell MD2SPRITE.C to use Z-buffer hacks to hide overdraw issues
-                                tsprShadow->extra |= TSPR_EXTRA_MDHACK;
+                                tsprShadow->clipdist |= TSPR_FLAGS_MDHACK;
                                 tsprShadow->cstat |= 512;
                             }
                             else