diff --git a/build-aux/flatpak/org.gnome.Calendar.json b/build-aux/flatpak/org.gnome.Calendar.json
index 06d06072..608b6299 100644
--- a/build-aux/flatpak/org.gnome.Calendar.json
+++ b/build-aux/flatpak/org.gnome.Calendar.json
@@ -119,6 +119,23 @@
                 }
             ]
         },
+        {
+            "name" : "gcr",
+            "buildsystem" : "meson",
+            "config-opts" : [
+                "-Dgtk_doc=false",
+                "-Dgtk3=false",
+                "-Dintrospection=false",
+                "-Dvapi=false"
+            ],
+            "sources" : [
+                {
+                    "type" : "git",
+                    "url" : "https://gitlab.gnome.org/GNOME/gcr.git",
+                    "branch" : "master"
+                }
+            ]
+        },
         {
             "name" : "evolution-data-server",
             "cleanup": [ "/share/GConf" ],
@@ -128,7 +145,8 @@
                 "-DENABLE_GOA=OFF",
                 "-DENABLE_DOT_LOCKING=OFF",
                 "-DENABLE_FILE_LOCKING=fcntl",
-                "-DENABLE_GTK=ON",
+                "-DENABLE_GTK=OFF",
+                "-DENABLE_GTK4=ON",
                 "-DENABLE_GOOGLE=OFF",
                 "-DENABLE_VALA_BINDINGS=OFF",
                 "-DENABLE_WEATHER=OFF",