diff --git a/nix/overlays/postgresql-libpq.nix b/nix/overlays/postgresql-libpq.nix
index 2d1841e60..bace97da4 100644
--- a/nix/overlays/postgresql-libpq.nix
+++ b/nix/overlays/postgresql-libpq.nix
@@ -1,6 +1,7 @@
 _: super:
 {
-  libpq = super.callPackage ../libpq.nix {
+  # Depending on which nixpkgs version is pinned, libpq might either be available already - or not.
+  libpq = super.libpq or (super.callPackage ../libpq.nix {
     postgresql = super.postgresql_16;
-  };
+  });
 }