diff --git a/src/doveadm/client-connection-tcp.c b/src/doveadm/client-connection-tcp.c
index 2097150bed..1af21c4c14 100644
--- a/src/doveadm/client-connection-tcp.c
+++ b/src/doveadm/client-connection-tcp.c
@@ -290,6 +290,11 @@ static bool client_handle_command_ctx(struct client_connection_tcp *conn,
 			doveadm_verbose = TRUE;
 			break;
 		case DOVEADM_PROTOCOL_CMD_FLAG_EXTRA_FIELDS:
+			if (argc == 0) {
+				e_error(cctx->event, "doveadm client: "
+					"Missing extra fields argument");
+				return FALSE;
+			}
 			cctx->extra_fields = t_strsplit_tabescaped(args[0]);
 			args++; argc--;
 			break;
@@ -299,6 +304,10 @@ static bool client_handle_command_ctx(struct client_connection_tcp *conn,
 			return FALSE;
 		}
 	}
+	if (argc < 2) {
+		e_error(cctx->event, "doveadm client: No command given");
+		return FALSE;
+	}
 	cctx->username = args[0]; args++; argc--;
 	cmd_name = args[0];