diff --git a/source/build/src/engine.cpp b/source/build/src/engine.cpp
index 17ba2f9ff..2aecddeee 100644
--- a/source/build/src/engine.cpp
+++ b/source/build/src/engine.cpp
@@ -4804,7 +4804,7 @@ static void classicDrawSprite(int32_t snum)
 
     if ((cstat&48)==48)
         vtilenum = tilenum; // if the game wants voxels, it gets voxels
-    else if (usevoxels && tiletovox[tilenum] != -1 && !(spriteext[spritenum].flags&SPREXT_NOTMD))
+    else if (usevoxels && tiletovox[tilenum] != -1 && spritenum != -1 && !(spriteext[spritenum].flags&SPREXT_NOTMD))
     {
         vtilenum = tiletovox[tilenum];
         cstat |= 48;