diff --git a/core/modules/system/tests/src/Functional/Update/README.txt b/core/modules/system/tests/src/Functional/Update/README.txt
new file mode 100644
index 0000000000..a8f97e3550
--- /dev/null
+++ b/core/modules/system/tests/src/Functional/Update/README.txt
@@ -0,0 +1,3 @@
+This folder contains tests of System module's hook_update_N() and
+hook_post_update_NAME() implementations. Tests of the update system should be
+placed in core/modules/system/tests/src/Functional/UpdateSystem.
diff --git a/core/modules/system/tests/src/Functional/UpdateSystem/README.txt b/core/modules/system/tests/src/Functional/UpdateSystem/README.txt
new file mode 100644
index 0000000000..c000bcab7b
--- /dev/null
+++ b/core/modules/system/tests/src/Functional/UpdateSystem/README.txt
@@ -0,0 +1,3 @@
+This folder contains tests of the update system. Test of System module's
+hook_update_N() and hook_post_update_NAME() implementations should be placed in
+core/modules/system/tests/src/Functional/Update.