Whoops. This should be signed correctly:
-----BEGIN BITCOIN SIGNED MESSAGE-----
Achow101_alt staking a new address 1AQx99s7q1wVinbgXbA48BaZQVWpHe5gYM on June 20th 2017. Current best block hash is 0000000000000000015e22405e714d4475cc70ef604641713e54478996f51fbb
-----BEGIN BITCOIN SIGNATURE-----
1At6EhbjN8BLCJz4pVAjsFcNzhzxQmXrwZ
HJJGQP+dF3O/81fMFPTcYCG2NnNRhJ1fzRth49Z8+PcrSL1LWcZ3jetQmikrYFwlk12cfB2hoL4tFJZjrfyr8CY=
-----END BITCOIN SIGNATURE-----