diff --git a/.github/workflows/benchmark.yml b/.github/workflows/benchmark.yml
index 45d6b131..4efd0d5c 100644
--- a/.github/workflows/benchmark.yml
+++ b/.github/workflows/benchmark.yml
@@ -16,6 +16,10 @@ concurrency:
 jobs:
   benchmark:
     runs-on: ubuntu-latest
+    env:
+      # Keep `uv run` from re-syncing the environment to the lockfile, which
+      # would undo the Triton 3.8 pin installed with `uv pip install`.
+      UV_NO_SYNC: "1"
 
     steps:
     - name: Checkout PR branch
@@ -44,15 +48,15 @@ jobs:
       run: |
         cd main-branch
         uv sync --extra test
-        uv pip install --pre -U triton
-        uv pip install "git+https://github.com/triton-lang/triton.git#subdirectory=python/triton_kernels"
+        uv pip install triton==3.8.0
+        uv pip install "git+https://github.com/triton-lang/triton.git@v3.8.0#subdirectory=python/triton_kernels"
 
     - name: Install PR dependencies
       run: |
         cd pr-branch
         uv sync --extra test
-        uv pip install --pre -U triton
-        uv pip install "git+https://github.com/triton-lang/triton.git#subdirectory=python/triton_kernels"
+        uv pip install triton==3.8.0
+        uv pip install "git+https://github.com/triton-lang/triton.git@v3.8.0#subdirectory=python/triton_kernels"
 
     - name: Run interleaved A/B benchmarks
       run: |
diff --git a/.github/workflows/python-app.yml b/.github/workflows/python-app.yml
index dc6026a8..d13e1fac 100644
--- a/.github/workflows/python-app.yml
+++ b/.github/workflows/python-app.yml
@@ -21,6 +21,10 @@ concurrency:
 jobs:
   build:
     runs-on: ubuntu-latest
+    env:
+      # Keep `uv run` from re-syncing the environment to the lockfile, which
+      # would undo the Triton 3.8 pin installed with `uv pip install`.
+      UV_NO_SYNC: "1"
 
     steps:
     - uses: actions/checkout@v3
@@ -48,11 +52,11 @@ jobs:
         cd tilelens
         uv sync --extra test
 
-    - name: Upgrade Triton to latest from main
+    - name: Install Triton 3.8
       run: |
         cd tilelens
-        uv pip install --pre -U triton
-        uv pip install "git+https://github.com/triton-lang/triton.git#subdirectory=python/triton_kernels"
+        uv pip install triton==3.8.0
+        uv pip install "git+https://github.com/triton-lang/triton.git@v3.8.0#subdirectory=python/triton_kernels"
 
     - name: Run frontend tests
       run: |
@@ -71,11 +75,11 @@ jobs:
         cd tilelens
         uv sync --extra test --extra nki
 
-    - name: Upgrade Triton to latest from main (NKI)
+    - name: Install Triton 3.8 (NKI)
       run: |
         cd tilelens
-        uv pip install --pre -U triton
-        uv pip install "git+https://github.com/triton-lang/triton.git#subdirectory=python/triton_kernels"
+        uv pip install triton==3.8.0
+        uv pip install "git+https://github.com/triton-lang/triton.git@v3.8.0#subdirectory=python/triton_kernels"
 
     - name: Run full (Triton + NKI) pytest suite
       run: |
diff --git a/pyproject.toml b/pyproject.toml
index cd498f0f..c58c7352 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -22,7 +22,7 @@ classifiers = [
 ]
 dependencies = [
   "setuptools",
-  "triton>=3.8.0",
+  "triton>=3.8.0,<3.9",
   "pyarrow",
   "pre-commit",
   "z3-solver==4.15.3.0",