diff --git a/newsfragments/650.misc b/newsfragments/650.misc
new file mode 100644
index 000000000..94f0ed982
--- /dev/null
+++ b/newsfragments/650.misc
@@ -0,0 +1 @@
+Format classes are now tested against invalid binary data with dials-data, for when dials-regression is not present.
diff --git a/tests/format/test_format.py b/tests/format/test_format.py
new file mode 100644
index 000000000..3b951ba8d
--- /dev/null
+++ b/tests/format/test_format.py
@@ -0,0 +1,12 @@
+from __future__ import annotations
+
+from dxtbx.format import Registry
+
+
+def test_reading_refl_failure(dials_data):
+    test_data = dials_data("centroid_test_data", pathlib=True)
+
+    # Without dials_regression, none of the dials-data tests check for this "invalid binary data" case
+    assert Registry.get_format_class_for_file(test_data / "indexed.refl") is None
+    # Check .expt while here
+    assert Registry.get_format_class_for_file(test_data / "indexed.expt") is None