diff --git a/static/js/blueslip.ts b/static/js/blueslip.ts
index 1c40e571b7..051c742430 100644
--- a/static/js/blueslip.ts
+++ b/static/js/blueslip.ts
@@ -177,7 +177,7 @@ function report_error(
 class BlueslipError extends Error {
     name = "BlueslipError";
     more_info?: unknown;
-    constructor(msg: string, more_info: unknown) {
+    constructor(msg: string, more_info?: unknown) {
         super(msg);
         if (more_info !== undefined) {
             this.more_info = more_info;
@@ -217,7 +217,7 @@ $(window).on("error", (event) => {
     report_error(message, ex.stack);
 });
 
-function build_arg_list(msg: string, more_info: unknown): [string, string?, unknown?] {
+function build_arg_list(msg: string, more_info?: unknown): [string, string?, unknown?] {
     const args: [string, string?, unknown?] = [msg];
     if (more_info !== undefined) {
         args.push("\nAdditional information: ", more_info);
@@ -225,22 +225,22 @@ function build_arg_list(msg: string, more_info: unknown): [string, string?, unkn
     return args;
 }
 
-export function debug(msg: string, more_info: unknown): void {
+export function debug(msg: string, more_info?: unknown): void {
     const args = build_arg_list(msg, more_info);
     logger.debug(...args);
 }
 
-export function log(msg: string, more_info: unknown): void {
+export function log(msg: string, more_info?: unknown): void {
     const args = build_arg_list(msg, more_info);
     logger.log(...args);
 }
 
-export function info(msg: string, more_info: unknown): void {
+export function info(msg: string, more_info?: unknown): void {
     const args = build_arg_list(msg, more_info);
     logger.info(...args);
 }
 
-export function warn(msg: string, more_info: unknown): void {
+export function warn(msg: string, more_info?: unknown): void {
     const args = build_arg_list(msg, more_info);
     logger.warn(...args);
     if (page_params.development_environment) {
@@ -248,7 +248,7 @@ export function warn(msg: string, more_info: unknown): void {
     }
 }
 
-export function error(msg: string, more_info: unknown, stack = new Error("dummy").stack): void {
+export function error(msg: string, more_info?: unknown, stack = new Error("dummy").stack): void {
     const args = build_arg_list(msg, more_info);
     logger.error(...args);
     report_error(msg, stack, {more_info});