diff --git a/changelog.d/15532.misc b/changelog.d/15532.misc
new file mode 100644
index 000000000000..e58273f2977d
--- /dev/null
+++ b/changelog.d/15532.misc
@@ -0,0 +1 @@
+Install the `xmlsec` package and switch back to the upstream [cachix/devenv](https://github.com/cachix/devenv) repo in the nix development environment.
diff --git a/flake.nix b/flake.nix
index 91916d9abb51..0afc4b22292c 100644
--- a/flake.nix
+++ b/flake.nix
@@ -97,6 +97,7 @@
 
                   # Native dependencies for unit tests (SyTest also requires OpenSSL).
                   openssl
+                  xmlsec
 
                   # Native dependencies for running Complement.
                   olm