diff --git a/lib/fudo/ssh.nix b/lib/fudo/ssh.nix
index 0ecbc45..2c8f254 100644
--- a/lib/fudo/ssh.nix
+++ b/lib/fudo/ssh.nix
@@ -45,7 +45,7 @@ in {
 
       hosts = mapAttrs (hostname: keypairs: {
         ssh-pubkeys = map (keypair: keypair.public-key) keypairs;
-        ssh-fingerprints = flatMap (keypair:
+        ssh-fingerprints = concatMap (keypair:
           let
             fingerprint-derivation = dns-sshfp-records hostname keypair;
             filename = sshfp-filename hostname keypair;