diff --git a/build.sh b/build.sh
index c6f44cc..1855cd6 100755
--- a/build.sh
+++ b/build.sh
@@ -75,8 +75,10 @@ if [ ! -f "keys/pubring.kbx" ]; then
     cat >foo_keys <<EOF
          %echo Generating a basic OpenPGP key
          Key-Type: RSA
+         Key-Usage: sign
          Key-Length: 4096
          Subkey-Type: RSA
+         Subkey-Usage: sign
          Subkey-Length: 4096
          Name-Real: ${KEY_NAME}
          Name-Comment: with stupid passphrase