diff --git a/tests/__init__.py b/tests/__init__.py
index 709e373..489096d 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -70,5 +70,7 @@ HAHA:YES
 END:FOO'''
 
 printable_characters_strategy = st.text(
-    st.characters(blacklist_categories=('Cc',))
+    st.characters(blacklist_categories=(
+        'Cc', 'Cs'
+    ))
 )
diff --git a/tests/cli/test_repair.py b/tests/cli/test_repair.py
index f550ea3..715049a 100644
--- a/tests/cli/test_repair.py
+++ b/tests/cli/test_repair.py
@@ -12,7 +12,7 @@ from vdirsyncer.utils.vobject import Item
 
 uid_strategy = st.text(st.characters(blacklist_categories=(
     'Zs', 'Zl', 'Zp',
-    'Cc'
+    'Cc', 'Cs'
 )))