diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8688809..521d534 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -35,7 +35,7 @@ jobs:
           - platform: "ubuntu-latest"
             python-version: "3.8"
           - platform: "ubuntu-latest"
-            python-version: "3.8"
+            python-version: "3.13"
           - platform: "macos-13"
             python-version: "3.8"
 
@@ -46,6 +46,7 @@ jobs:
         uses: actions/setup-python@v5
         with:
           python-version: ${{ matrix.python-version }}
+          allow-prereleases: true
 
       - uses: actions/cache@v4
         id: cache
diff --git a/pyproject.toml b/pyproject.toml
index 60b5563..239cc1e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -19,6 +19,7 @@ classifiers = [
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
 ]
 dynamic = ["version"]
 dependencies = [
@@ -32,11 +33,11 @@ dependencies = [
 legacy = ["imagecodecs"]
 tiff = ["tifffile"]
 test = [
-    "nd2[legacy]",
     "nd2[tiff]",
-    "aicsimageio",
+    "aicsimageio; python_version <= '3.12'",
     "dask[array]",
-    "lxml; python_version >= '3.9'",
+    "imagecodecs; python_version <= '3.12'",
+    "lxml; python_version >= '3.9' and python_version <= '3.12'",
     "numpy",
     "psutil",
     "pytest-codspeed",
diff --git a/src/nd2/tiff.py b/src/nd2/tiff.py
index 8ddf394..313b4f7 100644
--- a/src/nd2/tiff.py
+++ b/src/nd2/tiff.py
@@ -184,7 +184,7 @@ def position_iter(p: int) -> Iterator[np.ndarray]:
                     shape=shape,
                     dtype=nd2f.dtype,
                     resolution=(1 / pixelsize, 1 / pixelsize),
-                    resolutionunit=tf.TIFF.RESUNIT.MICROMETER,
+                    resolutionunit=tf.RESUNIT.MICROMETER,
                     photometric=photometric,
                     metadata=metadata,
                     description=ome_xml,