diff --git a/build-aux/flatpak/org.gnome.Calendar.json b/build-aux/flatpak/org.gnome.Calendar.json
index ab10fb1a..9e80eb6e 100644
--- a/build-aux/flatpak/org.gnome.Calendar.json
+++ b/build-aux/flatpak/org.gnome.Calendar.json
@@ -77,7 +77,8 @@
             "sources" : [
                 {
                     "type" : "git",
-                    "url" : "https://gitlab.gnome.org/GNOME/libgweather.git"
+                    "url" : "https://gitlab.gnome.org/GNOME/libgweather.git",
+                    "tag" : "40.0"
                 }
             ]
         },