diff --git a/src/pyrecest/utils/_point_set_registration_common.py b/src/pyrecest/utils/_point_set_registration_common.py
index ec6ea09cf..2fb04cde0 100644
--- a/src/pyrecest/utils/_point_set_registration_common.py
+++ b/src/pyrecest/utils/_point_set_registration_common.py
@@ -224,7 +224,7 @@ def _validate_tolerance(tolerance) -> float:
         raise ValueError("tolerance must be a finite non-negative scalar.")
 
     tolerance_scalar = tolerance_array.item()
-    if isinstance(tolerance_scalar, bool):
+    if isinstance(tolerance_scalar, (bool, str, bytes, bytearray)):
         raise ValueError("tolerance must be a finite non-negative scalar.")
 
     try:
diff --git a/tests/test_registration_loop_control_validation.py b/tests/test_registration_loop_control_validation.py
index 147de3d27..c8b93968e 100644
--- a/tests/test_registration_loop_control_validation.py
+++ b/tests/test_registration_loop_control_validation.py
@@ -45,6 +45,24 @@ def test_joint_registration_assignment_rejects_invalid_min_matches(self):
                         min_matches=bad_value,
                     )
 
+    @unittest.skipIf(
+        pyrecest.backend.__backend_name__ == "jax",
+        reason="Not supported on this backend",
+    )
+    def test_joint_registration_assignment_rejects_text_tolerance(self):
+        reference = array([[0.0, 0.0], [1.0, 0.0], [0.0, 1.0]])
+        moving = reference + array([1.0, -1.0])
+
+        for bad_value in ("0.1", b"0.1"):
+            with self.subTest(bad_value=bad_value):
+                with self.assertRaisesRegex(ValueError, "tolerance"):
+                    joint_registration_assignment(
+                        reference,
+                        moving,
+                        model="translation",
+                        tolerance=bad_value,
+                    )
+
     @unittest.skipIf(
         pyrecest.backend.__backend_name__ == "jax",
         reason="Not supported on this backend",