diff --git a/js/defs.js b/js/defs.js
index d1bb0dd..0f21e2c 100644
--- a/js/defs.js
+++ b/js/defs.js
@@ -142,11 +142,11 @@ export const COMPAT_FLAGS = [
 {
     key: 'no_auto_convert_ccl_popwalls',
     label: "Recessed walls under actors in CCL levels are left alone",
-    rulesets: new Set(['steam-strict']),
+    rulesets: new Set(['steam-strict', 'lynx', 'ms']),
 }, {
     key: 'no_auto_convert_ccl_blue_walls',
     label: "Blue walls under blocks in CCL levels are left alone",
-    rulesets: new Set(['steam-strict']),
+    rulesets: new Set(['steam-strict', 'lynx', 'ms']),
 },
 
 // Core
@@ -202,9 +202,13 @@ export const COMPAT_FLAGS = [
     key: 'traps_like_lynx',
     label: "Traps eject faster, and even when already open",
     rulesets: new Set(['lynx']),
+}, {
+    key: 'popwalls_pop_on_arrive',
+    label: "Recessed walls activate when stepped on",
+    rulesets: new Set(['lynx', 'ms']),
 }, {
     key: 'blue_floors_vanish_on_arrive',
-    label: "Fake blue walls vanish on arrival",
+    label: "Fake blue walls vanish when stepped on",
     rulesets: new Set(['lynx']),
 }, {
     key: 'green_teleports_can_fail',
diff --git a/js/tiletypes.js b/js/tiletypes.js
index b4b29c1..015fe92 100644
--- a/js/tiletypes.js
+++ b/js/tiletypes.js
@@ -357,16 +357,27 @@ const TILE_TYPES = {
                 me.type = TILE_TYPES['popwall2'];
             }
         },
+        activate(me, level, other) {
+            level.spawn_animation(me.cell, 'puff');
+            level.transmute_tile(me, 'wall');
+            if (other === level.player) {
+                level.sfx.play_once('popwall', me.cell);
+            }
+        },
+        on_arrive(me, level, other) {
+            // Lynx/MS: These activate on arrival, not departure
+            if (level.compat.popwalls_pop_on_arrive) {
+                this.activate(me, level, other);
+            }
+        },
         on_depart(me, level, other) {
             // CC2 quirk: nothing happens if there's still an actor on us (i.e. dynamite)
             // FIXME does this imply on_depart isn't called at all if we walk off dynamite?
             if (me.cell.has('dynamite_lit'))
                 return;
 
-            level.spawn_animation(me.cell, 'puff');
-            level.transmute_tile(me, 'wall');
-            if (other === level.player) {
-                level.sfx.play_once('popwall', me.cell);
+            if (! level.compat.popwalls_pop_on_arrive) {
+                this.activate(me, level, other);
             }
         },
     },