diff --git a/src/trainer_see.c b/src/trainer_see.c
index 348ec14c2d..4ac9c513b2 100644
--- a/src/trainer_see.c
+++ b/src/trainer_see.c
@@ -522,6 +522,9 @@ static u8 GetTrainerApproachDistance(struct ObjectEvent *trainerObj)
     PlayerGetDestCoords(&x, &y);
     if (trainerObj->trainerType == TRAINER_TYPE_NORMAL)  // can only see in one direction
     {
+        // Disable trainer approach while moving diagonally (usually moving on sideway stairs)
+        if (trainerObj->facingDirection > DIR_EAST)
+            return 0;
         approachDistance = sDirectionalApproachDistanceFuncs[trainerObj->facingDirection - 1](trainerObj, trainerObj->trainerRange_berryTreeId, x, y);
         return CheckPathBetweenTrainerAndPlayer(trainerObj, approachDistance, trainerObj->facingDirection);
     }