diff --git a/nix/libpq.nix b/nix/libpq.nix
index 6630ce5f8..ba82d65da 100644
--- a/nix/libpq.nix
+++ b/nix/libpq.nix
@@ -23,6 +23,7 @@ stdenv.mkDerivation {
 
   configureFlags = [
     "--without-gssapi"
+    "--without-icu"
     "--without-readline"
     "--with-openssl"
     "--with-system-tzdata=${tzdata}/share/zoneinfo"
diff --git a/nix/overlays/postgresql-libpq.nix b/nix/overlays/postgresql-libpq.nix
index c08a07ecb..5f342bd86 100644
--- a/nix/overlays/postgresql-libpq.nix
+++ b/nix/overlays/postgresql-libpq.nix
@@ -1,6 +1,6 @@
 self: super:
 {
   libpq = super.callPackage ../libpq.nix {
-    postgresql = super.postgresql_15;
+    postgresql = super.postgresql_16;
   };
 }