diff --git a/docs/translation_log.md b/docs/translation_log.md
index 0f33b75d..93568a92 100644
--- a/docs/translation_log.md
+++ b/docs/translation_log.md
@@ -660,12 +660,19 @@ worked around this by priming `wPlayerLastStopDirection = PLAYER_DIR_DOWN` in
 `.handleDirection`, before the turn-delay check. Removed the `wPlayerLastStopDirection`
 prime from `PlayerStepOutFromDoor`.
 
-### Cleanup — `LoadCurrentMapView` removed from `CollisionCheckOnLand`
+### `LoadCurrentMapView` in `CollisionCheckOnLand` — why it's required
 
-The previous session added `call LoadCurrentMapView` inside `CollisionCheckOnLand`,
-called on every direction press. `wTileMap` is always current at that point (built
-by `LoadWarpDestination` on map load, and by `AdvancePlayerSprite` on every
-block-boundary crossing), so the call was redundant every idle frame.
+`LoadCurrentMapView` rebuilds `wSurroundingTiles` from the block map AND copies a
+sub-block-offset viewport into `wTileMap` based on `W_Y_BLOCK_COORD`/`W_X_BLOCK_COORD`.
+`AdvancePlayerSprite` only calls it on block-boundary crossings. Between crossings
+YBC/XBC can advance 0→1 without triggering a rebuild, leaving `wTileMap` at the
+previous sub-block viewport offset. `GetTileInFrontOfPlayer` then reads the wrong tile.
+
+Symptom: walking toward a 2×2 cluster of impassable tiles (route 1 bushes, building
+outer walls, ledges) sporadically passes through — at the half-block sub-step the
+tile read lands on the adjacent passable tile instead of the correct one. The call is
+retained in `CollisionCheckOnLand`. A future optimisation could split out just the
+viewport-copy step (lines 1114–1135) since `wSurroundingTiles` is already current.
 
 ### Also in this commit
 
diff --git a/dos_port/src/overworld/overworld.asm b/dos_port/src/overworld/overworld.asm
index 41772d13..2b52c7d6 100644
--- a/dos_port/src/overworld/overworld.asm
+++ b/dos_port/src/overworld/overworld.asm
@@ -1369,6 +1369,11 @@ CollisionCheckOnLand:
     push eax
     push ecx
     push esi
+    ; wTileMap is a sub-block viewport into wSurroundingTiles, offset by W_Y_BLOCK_COORD /
+    ; W_X_BLOCK_COORD. AdvancePlayerSprite only calls LoadCurrentMapView on block-boundary
+    ; crossings, so the viewport can be stale within a block (YBC/XBC changed but wTileMap
+    ; not rebuilt). Rebuild here to apply the current sub-block offset before the tile read.
+    call LoadCurrentMapView
     call GetTileInFrontOfPlayer                    ; CL = tile in front
     call IsTilePassable                            ; CF = 1 if not passable
     pop esi