diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3c826a6..4957a86 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -30,9 +30,8 @@ jobs:
       - name: Lint with ruff
         run: ruff check src/ tests/
 
-      - name: Type check (ty — advisory)
+      - name: Type check (ty)
         if: matrix.python-version == '3.12'
-        continue-on-error: true
         run: |
           pip install ty==0.0.55
           ty check src
diff --git a/pyproject.toml b/pyproject.toml
index 29e49c6..0f2f859 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -51,4 +51,6 @@ testpaths = ["tests"]
 
 [tool.ruff]
 line-length = 100
-target-version = "py39"
\ No newline at end of file
+target-version = "py39"
+[tool.ty.environment]
+python-platform = "linux"
diff --git a/src/batch_probe/_probe_generic.py b/src/batch_probe/_probe_generic.py
index 3e27615..9b33d25 100644
--- a/src/batch_probe/_probe_generic.py
+++ b/src/batch_probe/_probe_generic.py
@@ -28,7 +28,7 @@ def _gpu_cleanup_generic(backend: str = "auto") -> None:
 
     if backend in ("auto", "cupy"):
         try:
-            import cupy as cp
+            import cupy as cp  # ty: ignore[unresolved-import]  # optional GPU backend
 
             pool = cp.get_default_memory_pool()
             pool.free_all_blocks()
@@ -40,7 +40,7 @@ def _gpu_cleanup_generic(backend: str = "auto") -> None:
 
     if backend in ("auto", "jax"):
         try:
-            import jax
+            import jax  # ty: ignore[unresolved-import]  # optional GPU backend
 
             jax.clear_caches()
         except (ImportError, AttributeError):
@@ -83,7 +83,7 @@ def probe(
 
     Example — CuPy::
 
-        import cupy as cp
+        import cupy as cp  # ty: ignore[unresolved-import]  # optional GPU backend
         from batch_probe import probe
 
         def my_work(n):
@@ -114,7 +114,7 @@ def my_work(n):
     except (ImportError, AttributeError):
         pass
     try:
-        import cupy as cp
+        import cupy as cp  # ty: ignore[unresolved-import]  # optional GPU backend
 
         oom_exceptions.append(cp.cuda.memory.OutOfMemoryError)
     except (ImportError, AttributeError):