diff --git a/news/3961.feature b/news/3961.feature
new file mode 100644
index 0000000..2c653dc
--- /dev/null
+++ b/news/3961.feature
@@ -0,0 +1,4 @@
+PloneFixture: explicitly install plone.app.contenttypes:default.
+The `addPloneSite` factory in Plone 6.1 no longer installs this by default.
+[maurits]
+
diff --git a/src/plone/app/testing/layers.py b/src/plone/app/testing/layers.py
index e1eb75b..6b787c3 100644
--- a/src/plone/app/testing/layers.py
+++ b/src/plone/app/testing/layers.py
@@ -70,7 +70,10 @@ class PloneFixture(Layer):
     )
 
     # Extension profiles to be installed with site setup
-    extensionProfiles = ("plonetheme.barceloneta:default",)
+    extensionProfiles = (
+        "plone.app.contenttypes:default",
+        "plonetheme.barceloneta:default",
+    )
 
     # Layer lifecycle