diff --git a/.github/workflows/build-test.yml b/.github/workflows/build-test.yml
index 733de82..6c79ba5 100644
--- a/.github/workflows/build-test.yml
+++ b/.github/workflows/build-test.yml
@@ -29,6 +29,9 @@ jobs:
         flake8 . --count --select=E9,F63,F7,F82 --show-source --statistics
         # exit-zero treats all errors as warnings. The GitHub editor is 127 chars wide
         flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
+    - name: Download testing data
+      run: |
+        python data/download.py
     - name: Test with pytest
       run: |
         pip install -r requirements-dev.txt
diff --git a/data/download.py b/data/download.py
index d050691..905da28 100755
--- a/data/download.py
+++ b/data/download.py
@@ -2,3 +2,32 @@
 
 from urllib.request import urlretrieve
 import os
+
+script_dir = os.path.dirname(os.path.realpath(__file__))
+
+# Data (file_name, sha512_hash)
+data = [
+    (
+        "Cell_3phase.tif",
+        "645cb8970de3370fb15835107843710e799f72f58012003db35b056160ad4de995622e12727d0b739a8afd1586c3faa178f3b71c39bd4dbc9308e8ef5ebb8e11",
+    ),
+    (
+        "Cell_5phase_small.tif",
+        "dd39269640efc251686f6e80bc42e3438e6f308274ca3d0b99e8da02f5976ad2cbd10cb594d2811631d0273413711096388b3a609eb41df2b04a1beeca4d91d1",
+    ),
+    (
+        "PSF_3phase.tif",
+        "80cc81d668bdcc6847599bb7eab477dd169024093b07ab743154d2e6df86471d955fba1234c9d728d28e2000be72f1f19677dad8f0e710f9c26fee1c3c0d2a3d",
+    ),
+    (
+        "PSF_5phase.tif",
+        "131f0621562a3832d270683c84d414acc20aacd7c1dae494dceef0cb156c170b6836f81544b80877978839a9eb82a882d3b5754040f6c098babd13be02f2d79e",
+    ),
+]
+
+for file_name, sha512_hash in data:
+    file_path = os.path.join(script_dir, file_name)
+    if not os.path.exists(file_path):
+        print(f"Downloading {file_name}")
+        url = f"https://data.kitware.com/api/v1/file/hashsum/sha512/{sha512_hash}/download"
+        urlretrieve(url, file_path)