diff --git a/src/test/modules/test_oat_hooks/expected/test_oat_hooks.out b/src/test/modules/test_oat_hooks/expected/test_oat_hooks.out
index c3a5067f44..194ee7ddb0 100644
--- a/src/test/modules/test_oat_hooks/expected/test_oat_hooks.out
+++ b/src/test/modules/test_oat_hooks/expected/test_oat_hooks.out
@@ -1,3 +1,7 @@
+-- This test script fails if debug_discard_caches is enabled, because cache
+-- flushes cause extra calls of the OAT hook in recomputeNamespacePath,
+-- resulting in more NOTICE messages than are in the expected output.
+SET debug_discard_caches = 0;
 -- Creating privileges on a placeholder GUC should create entries in the
 -- pg_parameter_acl catalog which conservatively grant no privileges to public.
 CREATE ROLE regress_role_joe;
diff --git a/src/test/modules/test_oat_hooks/sql/test_oat_hooks.sql b/src/test/modules/test_oat_hooks/sql/test_oat_hooks.sql
index d692f52d92..ebbd6a1d98 100644
--- a/src/test/modules/test_oat_hooks/sql/test_oat_hooks.sql
+++ b/src/test/modules/test_oat_hooks/sql/test_oat_hooks.sql
@@ -1,3 +1,8 @@
+-- This test script fails if debug_discard_caches is enabled, because cache
+-- flushes cause extra calls of the OAT hook in recomputeNamespacePath,
+-- resulting in more NOTICE messages than are in the expected output.
+SET debug_discard_caches = 0;
+
 -- Creating privileges on a placeholder GUC should create entries in the
 -- pg_parameter_acl catalog which conservatively grant no privileges to public.
 CREATE ROLE regress_role_joe;