diff --git a/library/fastd_key b/library/fastd_key
index 99e4982..06c76c8 100644
--- a/library/fastd_key
+++ b/library/fastd_key
@@ -23,7 +23,7 @@ if __name__ == '__main__':
     # create file with restrictive permissions
     with os.fdopen(os.open(path, os.O_WRONLY | os.O_CREAT, 0o600), 'w') as handle:
       # generate fastd secret
-      secret = subprocess.check_output(["fastd", "--machine-readable", "--generate-key"]).strip()
+      secret = subprocess.check_output(["fastd", "--machine-readable", "--generate-key"]).strip().decode()
       handle.write('secret "%s";\n' % secret)
 
     changed = True