diff --git a/tiled/_tests/test_slicer.py b/tiled/_tests/test_slicer.py
index 8e874d91c..5ad419d3c 100644
--- a/tiled/_tests/test_slicer.py
+++ b/tiled/_tests/test_slicer.py
@@ -129,8 +129,8 @@ def test_slicer_malicious_exec(slice: str):
         _ = slice_(slice)
 
 
-@pytest.mark.parametrize("slice", slice_typo_data + slice_malicious_data)
-def test_slicer_fastapi_query_rejectsion(slice, client):
+@pytest.mark.parametrize("slice_", slice_typo_data + slice_malicious_data)
+def test_slicer_fastapi_query_rejection(slice_, client):
     http_client = client.context.http_client
-    response = http_client.get(f"/api/v1/array/block/x?block=0&slice={slice}")
+    response = http_client.get(f"/api/v1/array/block/x?block=0&slice={slice_}")
     assert response.status_code == HTTP_422_UNPROCESSABLE_ENTITY
diff --git a/tiled/client/array.py b/tiled/client/array.py
index c0a89bec6..edfdffa5d 100644
--- a/tiled/client/array.py
+++ b/tiled/client/array.py
@@ -125,7 +125,7 @@ def read_block(self, block, slice=None):
 
     def read(self, slice=None):
         """
-        Acess the entire array or a slice.
+        Access the entire array or a slice.
 
         The array will be internally chunked with dask.
         """
diff --git a/tiled/server/dependencies.py b/tiled/server/dependencies.py
index 300f5ee43..f13c676fc 100644
--- a/tiled/server/dependencies.py
+++ b/tiled/server/dependencies.py
@@ -165,17 +165,17 @@ def expected_shape(
     return tuple(map(int, expected_shape.split(",")))
 
 
+def np_style_slicer(indices: tuple):
+    return indices[0] if len(indices) == 1 else slice_func(*indices)
+
+
+def parse_slice_str(dim: str):
+    return np_style_slicer(tuple(int(idx) if idx else None for idx in dim.split(":")))
+
+
 def slice_(
-    slice: str = Query(None, pattern=SLICE_REGEX),
+    slice: Optional[str] = Query(None, pattern=SLICE_REGEX),
 ):
     "Specify and parse a block index parameter."
 
-    def np_style_slicer(indices: tuple):
-        return indices[0] if len(indices) == 1 else slice_func(*indices)
-
-    def parse_slice_str(dim: str):
-        return np_style_slicer(
-            tuple(int(idx) if idx else None for idx in dim.split(":"))
-        )
-
     return tuple(parse_slice_str(dim) for dim in (slice or "").split(",") if dim)