diff --git a/config.go b/config.go
index f0e01f64..7b7b4056 100644
--- a/config.go
+++ b/config.go
@@ -1508,7 +1508,7 @@ func extractBitcoindRPCParams(bitcoindConfigPath string) (string, string, string
 // ZMQ rawblock and rawtx notifications are different.
 func checkZMQOptions(zmqBlockHost, zmqTxHost string) error {
 	if zmqBlockHost == zmqTxHost {
-		return errors.New("zmqpubrawblock and zmqpubrawtx must be set" +
+		return errors.New("zmqpubrawblock and zmqpubrawtx must be set " +
 			"to different addresses")
 	}