diff --git a/src/ifctester/test/ids_doc_generator.py b/src/ifctester/test/ids_doc_generator.py
index 1b6b16d221..f91decc1a7 100644
--- a/src/ifctester/test/ids_doc_generator.py
+++ b/src/ifctester/test/ids_doc_generator.py
@@ -310,7 +310,7 @@ spec = ifctester.ids.Specification(
 )
 specs.specifications.append(spec)
 spec.applicability.append(ifctester.ids.Entity(name="IFCWALLTYPE"))
-restriction = ifctester.ids.Restriction(options={"pattern": "(-|[0-9]{2,3})\/(-|[0-9]{2,3})\/(-|[0-9]{2,3})"})
+restriction = ifctester.ids.Restriction(options={"pattern": r"(-|[0-9]{2,3})/(-|[0-9]{2,3})/(-|[0-9]{2,3})"})
 spec.requirements.append(
     ifctester.ids.Property(
         propertySet="Pset_WallCommon",