diff --git a/_CoqProject b/_CoqProject
index f0ea2637c5ebd4f253b3633631aead76c55f23b3..36791391d121c77256719a3a24ccaf2df02749a3 100644
--- a/_CoqProject
+++ b/_CoqProject
@@ -5,6 +5,10 @@
 -arg -w -arg -redundant-canonical-projection
 # change_no_check does not exist yet in 8.9.
 -arg -w -arg -convert_concl_no_check
+# "Declare Scope" does not exist yet in 8.9.
+-arg -w -arg -undeclared-scope
+# We have ambiguous paths and so far it is not even clear what they are (https://gitlab.mpi-sws.org/iris/iris/issues/240).
+-arg -w -arg -ambiguous-paths
 
 theories/lifetime/model/boxes.v
 theories/lifetime/model/definitions.v