diff --git a/source/build/src/engine.cpp b/source/build/src/engine.cpp
index 233821b7c0f..db7cfbe42fd 100644
--- a/source/build/src/engine.cpp
+++ b/source/build/src/engine.cpp
@@ -855,62 +855,18 @@ int32_t nextsectorneighborz(int16_t sectnum, int32_t refz, int16_t topbottom, in
 //
 // cansee
 //
-int32_t cansee_old(int32_t xs, int32_t ys, int32_t zs, int16_t sectnums, int32_t xe, int32_t ye, int32_t ze, int16_t sectnume)
-{
-    sectortype *sec, *nsec;
-    walltype *wal, *wal2;
-    int32_t intx, inty, intz, i, cnt, nextsector, dasectnum, dacnt, danum;
-
-    if ((xs == xe) && (ys == ye) && (sectnums == sectnume)) return 1;
-    
-    clipsectorlist[0] = sectnums; danum = 1;
-    for(dacnt=0;dacnt<danum;dacnt++)
-    {
-        dasectnum = clipsectorlist[dacnt]; sec = &sector[dasectnum];
-        
-        for(cnt=sec->wallnum,wal=&wall[sec->wallptr];cnt>0;cnt--,wal++)
-        {
-            wal2 = &wall[wal->point2];
-            if (lintersect(xs,ys,zs,xe,ye,ze,wal->x,wal->y,wal2->x,wal2->y,&intx,&inty,&intz) != 0)
-            {
-                nextsector = wal->nextsector; if (nextsector < 0) return 0;
-
-                if (intz <= sec->ceilingz) return 0;
-                if (intz >= sec->floorz) return 0;
-                nsec = &sector[nextsector];
-                if (intz <= nsec->ceilingz) return 0;
-                if (intz >= nsec->floorz) return 0;
-
-                for(i=danum-1;i>=0;i--)
-                    if (clipsectorlist[i] == nextsector) break;
-                if (i < 0) clipsectorlist[danum++] = nextsector;
-            }
-        }
-
-        if (clipsectorlist[dacnt] == sectnume)
-            return 1;
-    }
-    return 0;
-}
 
 int32_t cansee(int32_t x1, int32_t y1, int32_t z1, int16_t sect1, int32_t x2, int32_t y2, int32_t z2, int16_t sect2)
 {
-    if (enginecompatibility_mode == ENGINECOMPATIBILITY_19950829)
-        return cansee_old(x1, y1, z1, sect1, x2, y2, z2, sect2);
-    int32_t dacnt, danum;
     const int32_t x21 = x2-x1, y21 = y2-y1, z21 = z2-z1;
 
-    static uint8_t sectbitmap[(MAXSECTORS+7)>>3];
-    memset(sectbitmap, 0, sizeof(sectbitmap));
     if (x1 == x2 && y1 == y2)
         return (sect1 == sect2);
 
-    sectbitmap[sect1>>3] |= (1 << (sect1&7));
-    clipsectorlist[0] = sect1; danum = 1;
+    BFSSearch search(numsectors, sect1);
 
-    for (dacnt=0; dacnt<danum; dacnt++)
+    for (int dasectnum; (dasectnum = search.GetNext()) != BFSSearch::EOL;)
     {
-        const int32_t dasectnum = clipsectorlist[dacnt];
         auto const sec = (usectorptr_t)&sector[dasectnum];
         uwallptr_t wal;
         bssize_t cnt;
@@ -953,19 +909,11 @@ int32_t cansee(int32_t x1, int32_t y1, int32_t z1, int16_t sect1, int32_t x2, in
             if (z <= cfz[0] || z >= cfz[1])
                 return 0;
 
-            if (!(sectbitmap[nexts>>3] & (1 << (nexts&7))))
-            {
-                sectbitmap[nexts>>3] |= (1 << (nexts&7));
-                clipsectorlist[danum++] = nexts;
-            }
+            search.Add(nexts);
         }
 
     }
-
-    if (sectbitmap[sect2>>3] & (1<<(sect2&7)))
-        return 1;
-
-    return 0;
+    return search.Check(sect2);
 }
 
 //