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LShiftFix

Fixed an issue where holding the left shift key wouldn't let you jump when playing MC 1.8.9 while using multiple input methods.

Forge
Loaders
Forge
Downloads on Modrinth
194
Followers on Modrinth
0
version
1
Updated
July 19, 2026Jul 19
Published
in 2026

At a glance

Runs on Forge
For Minecraft 1.8.9
Needed in the game; optional on the server
Latest version — 1.0.0 from July 19, 2026
Requires MixinBooter
License MIT — free
Where it's needed
In gamerequiredOn serveroptional

Needed in the game; optional on the server

Game versions1.8.9

Problem When a Chinese / Japanese / Korean IME is active in Minecraft 1.8.9, the player cannot jump while holding Shift (sneak) and pressing Space. The jump input is swallowed by the OS input method.

Root cause: Almost every IME registers Shift+Space as a full-width/half-width toggle hotkey. Windows routes WM_KEYDOWN through ImmTranslateMessage before dispatching to the app. The IME consumes the combo there, so Minecraft's Keyboard.next() event queue never sees the key press — keyBindJump.isKeyDown() stays false forever.

Fix LShiftFix injects at the tail of EntityPlayerSP.updateMovementInput():

Reads the player's bound jump key (default Space, supports rebinding) Calls Keyboard.isKeyDown(keyCode) to directly poll the hardware state If physically pressed but movementInput.jump is still false, force it to true LWJGL's keyDownBuffer is populated by WindowProc at a layer lower than WM_KEYDOWN, so IME interception of the event queue doesn't affect it. The fix is IME-agnostic — works for Sogou, Microsoft Pinyin, QQ Pinyin, Google Input, Japanese IME, Korean IME, etc.

FAQ

How to install LShiftFix?

Install Forge for your Minecraft version, download LShiftFix for the same version and loader, put the file into the mods folder and launch the game with the loader profile.

Which Minecraft versions does LShiftFix support?

LShiftFix has builds for Minecraft 1.8.9.

Is LShiftFix needed on the server?

Needed in the game; optional on the server

License and source
MIT Licensefree to use and share with credit to the author
Original — Modrinth↗Files unchanged, verified with SHA-512Is this your mod? For rights holders

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