diff --git a/Entities/UpsideDownJumpThru.cs b/Entities/UpsideDownJumpThru.cs
index 4b46977..b19282f 100644
--- a/Entities/UpsideDownJumpThru.cs
+++ b/Entities/UpsideDownJumpThru.cs
@@ -21,6 +21,8 @@ class UpsideDownJumpThru : JumpThru {
 
         private static ILHook playerOrigUpdateHook;
 
+        private static readonly Hitbox normalHitbox = new Hitbox(8f, 11f, -4f, -11f);
+
         public static void Load() {
             using (new DetourContext { Before = { "*" } }) { // these don't always call the orig methods, better apply them first.
                 // fix general actor/platform behavior to make them comply with jumpthrus.
@@ -42,6 +44,9 @@ public static void Load() {
                 playerOrigUpdateHook = new ILHook(typeof(Player).GetMethod("orig_Update"), filterOutJumpThrusFromCollideChecks);
                 IL.Celeste.Player.DashUpdate += filterOutJumpThrusFromCollideChecks;
                 IL.Celeste.Player.RedDashUpdate += filterOutJumpThrusFromCollideChecks;
+
+                // listen for the player unducking, to knock the player down before they would go through upside down jumpthrus.
+                On.Celeste.Player.Update += onPlayerUpdate;
             }
         }
 
@@ -55,6 +60,8 @@ public static void Unload() {
             playerOrigUpdateHook?.Dispose();
             IL.Celeste.Player.DashUpdate -= filterOutJumpThrusFromCollideChecks;
             IL.Celeste.Player.RedDashUpdate -= filterOutJumpThrusFromCollideChecks;
+
+            On.Celeste.Player.Update -= onPlayerUpdate;
         }
 
         private static bool onActorMoveVExact(On.Celeste.Actor.orig_MoveVExact orig, Actor self, int moveV, Collision onCollide, Solid pusher) {
@@ -289,6 +296,25 @@ private static void patchPlayerClimbUpdate(ILContext il) {
             }
         }
 
+        private static void onPlayerUpdate(On.Celeste.Player.orig_Update orig, Player self) {
+            bool unduckWouldGoThroughPlatform = self.Ducking && !self.CollideCheck<UpsideDownJumpThru>();
+            if (unduckWouldGoThroughPlatform) {
+                Collider bak = self.Collider;
+                self.Collider = normalHitbox;
+                unduckWouldGoThroughPlatform = self.CollideCheck<UpsideDownJumpThru>();
+                self.Collider = bak;
+            }
+
+            orig(self);
+
+            if (unduckWouldGoThroughPlatform && !self.Ducking) {
+                // we just unducked, and are now inside an upside-down jumpthru.
+                // knock the player down if possible!
+                while (self.CollideCheck<UpsideDownJumpThru>() && !self.CollideCheck<Solid>(self.Position + new Vector2(0f, 1f))) {
+                    self.Position.Y++;
+                }
+            }
+        }