diff --git a/ChangeLog.txt b/ChangeLog.txt
index 2b4a93bf..f2123f6f 100644
--- a/ChangeLog.txt
+++ b/ChangeLog.txt
@@ -18,6 +18,8 @@ Broker:
   PUBREL, PUBCOMP without disconnecting. Closes #57.
 - Fix websockets listeners not being able to bind to an IP address. Closes
   #170.
+- mosquitto_passwd utility now correctly deals with unknown command line
+  arguments in all cases. Closes #169.
 
 Client library:
 - Fix the case where a message received just before the keepalive timer
diff --git a/src/mosquitto_passwd.c b/src/mosquitto_passwd.c
index 4a9ffeee..a7ad1cca 100644
--- a/src/mosquitto_passwd.c
+++ b/src/mosquitto_passwd.c
@@ -369,6 +369,7 @@ int main(int argc, char *argv[])
 			batch_mode = true;
 		}else{
 			fprintf(stderr, "Error: Unknown option '%s'\n", argv[1]);
+			return 1;
 		}
 		password_file_tmp = argv[2];
 		username = argv[3];