diff --git a/org.gnome.Calendar.json b/build-aux/flatpak/org.gnome.Calendar.json
similarity index 100%
rename from org.gnome.Calendar.json
rename to build-aux/flatpak/org.gnome.Calendar.json
diff --git a/build-aux/flatpak/org.gnome.Calendar.json~ b/build-aux/flatpak/org.gnome.Calendar.json~
new file mode 100644
index 00000000..c78da1a8
--- /dev/null
+++ b/build-aux/flatpak/org.gnome.Calendar.json~
@@ -0,0 +1,172 @@
+{
+    "app-id" : "org.gnome.Calendar",
+    "runtime" : "org.gnome.Platform",
+    "runtime-version" : "master",
+    "sdk" : "org.gnome.Sdk",
+    "command" : "gnome-calendar",
+    "tags" : [
+        "devel"
+    ],
+    "desktop-file-name-prefix" : "(Development) ",
+    "finish-args" : [
+        "--share=ipc",
+        "--share=network",
+        "--socket=x11",
+        "--socket=wayland",
+        "--system-talk-name=org.freedesktop.login1",
+        "--system-talk-name=org.freedesktop.GeoClue2",
+        "--talk-name=ca.desrt.dconf",
+        "--talk-name=org.gnome.ControlCenter",
+        "--talk-name=org.gnome.OnlineAccounts",
+        "--talk-name=org.gnome.evolution.dataserver.AddressBook9",
+        "--talk-name=org.gnome.evolution.dataserver.Calendar7",
+        "--talk-name=org.gnome.evolution.dataserver.Sources5",
+        "--talk-name=org.gnome.evolution.dataserver.Subprocess.Backend.*",
+        "--filesystem=home",
+        "--filesystem=xdg-run/dconf",
+        "--filesystem=~/.config/dconf:ro",
+        "--env=DCONF_USER_CONFIG_DIR=.config/dconf"
+    ],
+    "build-options" : {
+        "cflags" : "-O2 -g",
+        "cxxflags" : "-O2 -g",
+        "env" : {
+            "V" : "1"
+        }
+    },
+    "x-run-args" : [
+        "--debug"
+    ],
+    "cleanup" : [
+        "/include",
+        "/lib/pkgconfig",
+        "/share/pkgconfig",
+        "/share/aclocal",
+        "/man",
+        "/share/man",
+        "/share/gtk-doc",
+        "*.la",
+        "*.a"
+    ],
+    "modules" : [
+        {
+            "name" : "gnome-online-accounts",
+            "config-opts" : [
+                "--disable-Werror",
+                "--disable-telepathy",
+                "--disable-documentation",
+                "--disable-backend"
+            ],
+            "sources" : [
+                {
+                    "type" : "git",
+                    "url" : "https://gitlab.gnome.org/GNOME/gnome-online-accounts.git"
+                }
+            ]
+        },
+        {
+            "name" : "libical",
+            "cleanup" : [
+                "/lib/cmake"
+            ],
+            "buildsystem" : "cmake",
+            "config-opts" : [
+                "-DCMAKE_INSTALL_LIBDIR:PATH=/app/lib",
+                "-DBUILD_SHARED_LIBS:BOOL=ON"
+            ],
+            "sources" : [
+                {
+                    "type" : "archive",
+                    "url" : "https://github.com/libical/libical/releases/download/v3.0.1/libical-3.0.1.tar.gz",
+                    "sha256" : "7f32a889df542592a357a73ff5f3bd7b5058450c1a3fb272b1c9a69e32d9ed10"
+                }
+            ]
+        },
+        {
+            "name" : "geocode-glib",
+            "buildsystem" : "meson",
+            "builddir" : true,
+            "config-opts" : [
+                "--libdir=/app/lib"
+            ],
+            "sources" : [
+                {
+                    "type" : "git",
+                    "url" : "https://gitlab.gnome.org/GNOME/geocode-glib.git"
+                }
+            ]
+        },
+        {
+            "name" : "libgweather",
+            "buildsystem" : "meson",
+            "config-opts" : [
+                "--libdir=/app/lib"
+            ],
+            "sources" : [
+                {
+                    "type" : "git",
+                    "url" : "https://gitlab.gnome.org/GNOME/libgweather.git"
+                }
+            ]
+        },
+        {
+            "name" : "evolution-data-server",
+            "cleanup" : [
+                "/lib/cmake",
+                "/lib/evolution-data-server/*-backends",
+                "/libexec",
+                "/share/dbus-1/services"
+            ],
+            "buildsystem" : "cmake",
+            "config-opts" : [
+                "-DENABLE_GTK=ON",
+                "-DENABLE_GOOGLE_AUTH=OFF",
+                "-DENABLE_UOA=OFF",
+                "-DENABLE_GOOGLE=OFF",
+                "-DENABLE_VALA_BINDINGS=OFF",
+                "-DENABLE_WEATHER=OFF",
+                "-DWITH_OPENLDAP=OFF",
+                "-DWITH_LIBDB=OFF",
+                "-DENABLE_INTROSPECTION=OFF",
+                "-DENABLE_INSTALLED_TESTS=OFF",
+                "-DENABLE_GTK_DOC=OFF",
+                "-DENABLE_EXAMPLES=OFF"
+            ],
+            "sources" : [
+                {
+                    "type" : "git",
+                    "url" : "https://gitlab.gnome.org/GNOME/evolution-data-server.git"
+                }
+            ]
+        },
+        {
+            "name" : "libdazzle",
+            "config-opts" : [
+                "--libdir=/app/lib",
+                "--buildtype=debugoptimized"
+            ],
+            "buildsystem" : "meson",
+            "builddir" : true,
+            "sources" : [
+                {
+                    "type" : "git",
+                    "url" : "https://gitlab.gnome.org/GNOME/libdazzle.git"
+                }
+            ]
+        },
+        {
+            "name" : "gnome-calendar",
+            "buildsystem" : "meson",
+            "sources" : [
+                {
+                    "type" : "git",
+                    "url" : "https://gitlab.gnome.org/GNOME/gnome-calendar.git"
+                }
+            ],
+            "config-opts" : [
+                "-Dtracing=true",
+                "-Ddocumentation=true"
+            ]
+        }
+    ]
+}
diff --git a/build-aux/meson.build b/build-aux/meson.build
new file mode 100644
index 00000000..8800f009
--- /dev/null
+++ b/build-aux/meson.build
@@ -0,0 +1 @@
+subdir('meson')
diff --git a/build-aux/meson/meson.build b/build-aux/meson/meson.build
new file mode 100644
index 00000000..1ab810bb
--- /dev/null
+++ b/build-aux/meson/meson.build
@@ -0,0 +1 @@
+meson.add_install_script('meson_post_install.py')
diff --git a/meson_post_install.py b/build-aux/meson/meson_post_install.py
similarity index 100%
rename from meson_post_install.py
rename to build-aux/meson/meson_post_install.py
diff --git a/meson.build b/meson.build
index 00c6a20f..c660e254 100644
--- a/meson.build
+++ b/meson.build
@@ -167,6 +167,7 @@ src_dir = join_paths(meson.source_root(), 'src')
 # Subdirs #
 ###########
 
+subdir('build-aux')
 subdir('contrib')
 subdir('data')
 subdir('src')
@@ -182,8 +183,6 @@ configure_file(
   configuration: config_h
 )
 
-meson.add_install_script('meson_post_install.py')
-
 output = '\n\n      GNOME Calendar ' + calendar_version + '\n'
 output += '      =========================\n\n'
 output += '          Source ..........................: ' + meson.source_root() + '\n'