diff --git a/studio/install_llama_prebuilt.py b/studio/install_llama_prebuilt.py
index 13382d3c16..9fe5b55e9f 100755
--- a/studio/install_llama_prebuilt.py
+++ b/studio/install_llama_prebuilt.py
@@ -60,7 +60,7 @@ def env_int(name: str, default: int, *, minimum: int | None = None) -> int:
     return value
 
 
-DEFAULT_LLAMA_TAG = os.environ.get("UNSLOTH_LLAMA_TAG", "master")
+DEFAULT_LLAMA_TAG = os.environ.get("UNSLOTH_LLAMA_TAG", "b8637")
 # Force all installs to use mainline llama.cpp from ggml-org.
 # Previously: DEFAULT_PUBLISHED_REPO = os.environ.get("UNSLOTH_LLAMA_RELEASE_REPO", "unslothai/llama.cpp")
 DEFAULT_PUBLISHED_REPO = "ggml-org/llama.cpp"
diff --git a/studio/setup.ps1 b/studio/setup.ps1
index 382de89b9f..47d7f0ee55 100644
--- a/studio/setup.ps1
+++ b/studio/setup.ps1
@@ -29,7 +29,7 @@ $PackageDir = Split-Path -Parent $ScriptDir
 # --------------------------------------------------------------------------
 $DefaultLlamaPrForce = ""
 $DefaultLlamaSource = "https://github.com/ggml-org/llama.cpp"
-$DefaultLlamaTag = "master"
+$DefaultLlamaTag = "b8637"
 
 # Verbose can be enabled either by CLI flag or by UNSLOTH_VERBOSE=1.
 $script:UnslothVerbose = ($env:UNSLOTH_VERBOSE -eq '1')
diff --git a/studio/setup.sh b/studio/setup.sh
index 76fd79e7a2..4e7bd366ef 100755
--- a/studio/setup.sh
+++ b/studio/setup.sh
@@ -19,7 +19,7 @@ RULE=$(printf '\342\224\200%.0s' {1..52})
 # ──────────────────────────────────────────────────────────────────────────
 _DEFAULT_LLAMA_PR_FORCE=""
 _DEFAULT_LLAMA_SOURCE="https://github.com/ggml-org/llama.cpp"
-_DEFAULT_LLAMA_TAG="master"
+_DEFAULT_LLAMA_TAG="b8637"
 
 # ── Colors (same palette as startup_banner / install_python_stack) ──
 if [ -n "${NO_COLOR:-}" ]; then