diff --git a/doc/fixes36.1 b/doc/fixes36.1
index ec5d44b9e..b44ce9f4b 100644
--- a/doc/fixes36.1
+++ b/doc/fixes36.1
@@ -84,6 +84,7 @@ guard macros available for mextra fields similar to those for oextra fields
 compile-time option for an alternate paniclog format for public server use
 make monsters forget where they stepped when fleeing or teleporting
 requiver pickup_thrown objects if quiver is empty
+make mimics mimicing walls or trees also block light
 
 
 Platform- and/or Interface-Specific Fixes
diff --git a/include/monst.h b/include/monst.h
index 3c88d0172..7196026f9 100644
--- a/include/monst.h
+++ b/include/monst.h
@@ -159,6 +159,16 @@ struct monst {
 #define is_vampshifter(mon)                                      \
     ((mon)->cham == PM_VAMPIRE || (mon)->cham == PM_VAMPIRE_LORD \
      || (mon)->cham == PM_VLAD_THE_IMPALER)
+
+/* mimic appearances that block vision/light */
+#define is_lightblocker_mappear(mon)                    \
+    (is_obj_mappear(mon, BOULDER) ||                    \
+     ((mon)->m_ap_type == M_AP_FURNITURE                \
+      && ((mon)->mappearance == S_hcdoor                \
+          || (mon)->mappearance == S_vcdoor             \
+          || (mon)->mappearance < S_ndoor /* = walls */ \
+          || (mon)->mappearance == S_tree)))
+
 #define is_door_mappear(mon) ((mon)->m_ap_type == M_AP_FURNITURE \
      && ((mon)->mappearance == S_hcdoor || (mon)->mappearance == S_vcdoor))
 #define is_obj_mappear(mon,otyp) ((mon)->m_ap_type == M_AP_OBJECT \
diff --git a/src/display.c b/src/display.c
index e75f74d53..333ed4d5b 100644
--- a/src/display.c
+++ b/src/display.c
@@ -1201,8 +1201,7 @@ set_mimic_blocking()
     for (mon = fmon; mon; mon = mon->nmon) {
         if (DEADMONSTER(mon))
             continue;
-        if (mon->minvis && (is_door_mappear(mon)
-                            || is_obj_mappear(mon,BOULDER))) {
+        if (mon->minvis && is_lightblocker_mappear(mon)) {
             if (See_invisible)
                 block_point(mon->mx, mon->my);
             else
diff --git a/src/mon.c b/src/mon.c
index 40cdb0dca..3c272cbc7 100644
--- a/src/mon.c
+++ b/src/mon.c
@@ -2616,8 +2616,7 @@ void
 seemimic(mtmp)
 register struct monst *mtmp;
 {
-    boolean is_blocker_appear = (is_door_mappear(mtmp)
-                                 || is_obj_mappear(mtmp, BOULDER));
+    boolean is_blocker_appear = (is_lightblocker_mappear(mtmp));
 
     if (has_mcorpsenm(mtmp))
         freemcorpsenm(mtmp);
diff --git a/src/vision.c b/src/vision.c
index 77475af96..2dcc85b8b 100644
--- a/src/vision.c
+++ b/src/vision.c
@@ -175,9 +175,9 @@ register struct rm *lev;
         if (obj->otyp == BOULDER)
             return 1;
 
-    /* Mimics mimicing a door or boulder block light. */
+    /* Mimics mimicing a door or boulder or ... block light. */
     if ((mon = m_at(x, y)) && (!mon->minvis || See_invisible)
-        && (is_door_mappear(mon) || is_obj_mappear(mon,BOULDER)))
+        && is_lightblocker_mappear(mon))
         return 1;
 
     return 0;