diff --git a/include/extern.h b/include/extern.h
index 3a0c6183f..f6063cef9 100644
--- a/include/extern.h
+++ b/include/extern.h
@@ -3502,6 +3502,7 @@ extern int assign_videocolors(char *) NONNULLARG1;
 
 /* ### vision.c ### */
 
+extern boolean get_viz_clear(int, int);
 extern void vision_init(void);
 extern int does_block(int, int, struct rm *) NONNULLARG3;
 extern void vision_reset(void);
diff --git a/src/apply.c b/src/apply.c
index 60384c3aa..676d97137 100644
--- a/src/apply.c
+++ b/src/apply.c
@@ -452,6 +452,7 @@ use_stethoscope(struct obj *obj)
         Soundeffect(se_hollow_sound, 100);
         You_hear(hollow_str, "door");
         cvt_sdoor_to_door(lev); /* ->typ = DOOR */
+        recalc_block_point(rx, ry);
         feel_newsym(rx, ry);
         return res;
     case SCORR:
diff --git a/src/detect.c b/src/detect.c
index ccede5c5d..cb6dc2458 100644
--- a/src/detect.c
+++ b/src/detect.c
@@ -1651,6 +1651,7 @@ findone(coordxy zx, coordxy zy, genericptr_t whatfound)
 
         flash_glyph_at(zx, zy, cmap_to_glyph(sym), FOUND_FLASH_COUNT);
         cvt_sdoor_to_door(lev); /* set lev->typ = DOOR */
+        recalc_block_point(zx, zy);
         magic_map_background(zx, zy, 0);
         foundone(zx, zy, back_to_glyph(zx, zy));
         found_p->num_sdoors++;
@@ -2040,6 +2041,7 @@ dosearch0(int aflag) /* intrinsic autosearch vs explicit searching */
                     if (rnl(7 - fund))
                         continue;
                     cvt_sdoor_to_door(&levl[x][y]); /* .typ = DOOR */
+                    recalc_block_point(x, y);
                     exercise(A_WIS, TRUE);
                     nomul(0);
                     feel_location(x, y); /* make sure it shows up */
diff --git a/src/dig.c b/src/dig.c
index cb064c53c..2e028b035 100644
--- a/src/dig.c
+++ b/src/dig.c
@@ -541,6 +541,7 @@ dig(void)
         if (IS_DOOR(lev->typ) && (lev->doormask & D_TRAPPED)) {
             lev->doormask = D_NODOOR;
             b_trapped("door", NO_PART);
+            recalc_block_point(dpx, dpy);
             newsym(dpx, dpy);
         }
  cleanup:
@@ -1682,7 +1683,7 @@ zap_dig(void)
                 pline_The("door is razed!");
             watch_dig((struct monst *) 0, zx, zy, TRUE);
             room->doormask = D_NODOOR;
-            unblock_point(zx, zy); /* vision */
+            recalc_block_point(zx, zy); /* vision */
             digdepth -= 2;
             if (maze_dig)
                 break;
diff --git a/src/muse.c b/src/muse.c
index 22948330a..264d6b9ab 100644
--- a/src/muse.c
+++ b/src/muse.c
@@ -758,8 +758,7 @@ reveal_trap(struct trap *t, boolean seeit)
 
     if (lev->typ == SCORR) {
         lev->typ = CORR, lev->flags = 0; /* set_levltyp(,,CORR) */
-        if (seeit)
-            unblock_point(t->tx, t->ty);
+        unblock_point(t->tx, t->ty);
     }
     if (seeit)
         seetrap(t);
diff --git a/src/read.c b/src/read.c
index 47c4d2594..831d85118 100644
--- a/src/read.c
+++ b/src/read.c
@@ -2035,8 +2035,11 @@ seffect_magic_mapping(struct obj **sobjp)
 
             for (x = 1; x < COLNO; x++)
                 for (y = 0; y < ROWNO; y++)
-                    if (levl[x][y].typ == SDOOR)
+                    if (levl[x][y].typ == SDOOR) {
                         cvt_sdoor_to_door(&levl[x][y]);
+                        if (Is_rogue_level(&u.uz))
+                            unblock_point(x, y);
+                    }
             /* do_mapping() already reveals secret passages */
         }
         gk.known = TRUE;
diff --git a/src/vision.c b/src/vision.c
index e3d771a04..3f33d726c 100644
--- a/src/vision.c
+++ b/src/vision.c
@@ -100,6 +100,15 @@ staticfn void rogue_vision(seenV **, coordxy *, coordxy *);
 #define sign(z) ((z) < 0 ? -1 : ((z) ? 1 : 0))
 #define v_abs(z) ((z) < 0 ? -(z) : (z)) /* don't use abs -- it may exist */
 
+/* expose viz_clear[][] for sanity checking */
+boolean
+get_viz_clear(int x, int y)
+{
+    if (isok(x,y) && !viz_clear[y][x])
+        return TRUE;
+    return FALSE;
+}
+
 /*
  * vision_init()
  *
diff --git a/src/wizcmds.c b/src/wizcmds.c
index 948b63fe6..a22b6883d 100644
--- a/src/wizcmds.c
+++ b/src/wizcmds.c
@@ -20,6 +20,7 @@ staticfn void mon_chain(winid, const char *, struct monst *, boolean, long *,
 staticfn void contained_stats(winid, const char *, long *, long *);
 staticfn void misc_stats(winid, long *, long *);
 staticfn void you_sanity_check(void);
+staticfn void levl_sanity_check(void);
 staticfn void makemap_unmakemon(struct monst *, boolean);
 staticfn int QSORTCALLBACK migrsort_cmp(const genericptr, const genericptr);
 staticfn void list_migrating_mons(d_level *);
@@ -1437,6 +1438,22 @@ you_sanity_check(void)
     (void) check_invent_gold("invent");
 }
 
+staticfn void
+levl_sanity_check(void)
+{
+    coordxy x, y;
+
+    if (Underwater)
+        return; /* Underwater uses different vision */
+
+    for (y = 0; y < ROWNO; y++) {
+        for (x = 1; x < COLNO; x++) {
+            if ((does_block(x, y, &levl[x][y]) ? 1 : 0) != get_viz_clear(x, y))
+                impossible("levl[%i][%i] vision blocking", x, y);
+        }
+    }
+}
+
 void
 sanity_check(void)
 {
@@ -1457,6 +1474,7 @@ sanity_check(void)
     bc_sanity_check();
     trap_sanity_check();
     engraving_sanity_check();
+    levl_sanity_check();
     program_state.in_sanity_check--;
 }
 
diff --git a/src/zap.c b/src/zap.c
index b367722f3..7fc54146e 100644
--- a/src/zap.c
+++ b/src/zap.c
@@ -3707,6 +3707,7 @@ zap_map(
         /* secret door gets revealed, converted into regular door */
         if (ltyp == SDOOR) {
             cvt_sdoor_to_door(&levl[x][y]); /* .typ = DOOR */
+            recalc_block_point(x, y);
             newsym(x, y);
             if (cansee(x, y)) {
                 pline("Probing reveals a secret door.");
@@ -5331,6 +5332,7 @@ zap_over_floor(
     /* secret door gets revealed, converted into regular door */
     if (levl[x][y].typ == SDOOR) {
         cvt_sdoor_to_door(&levl[x][y]); /* .typ = DOOR */
+        recalc_block_point(x, y);
         /* target spot will now pass closed_door() test below
            (except on rogue level) */
         newsym(x, y);