diff --git a/src/interfaces/github.ts b/src/interfaces/github.ts
index 25a1838..af65839 100644
--- a/src/interfaces/github.ts
+++ b/src/interfaces/github.ts
@@ -1,10 +1,10 @@
 export interface ICheckOutput {
   title: string;
   message: string;
-  conclusion: string;
+  conclusion: "success" | "failure";
 }
 
 export interface ICreateCheckOutput {
   checkId: number;
-  detailsUrl: string | null;
+  detailsUrl: string | undefined;
 }
diff --git a/src/services/checkRunsService.ts b/src/services/checkRunsService.ts
index d02ae62..946a7e9 100644
--- a/src/services/checkRunsService.ts
+++ b/src/services/checkRunsService.ts
@@ -111,7 +111,7 @@ export const createCheckRun = async (
     });
     return {
       checkId: response.data.id,
-      detailsUrl: response.data.html_url,
+      detailsUrl: response.data.html_url || undefined,
     };
   } catch (error) {
     console.log(error);
diff --git a/src/utils/message.ts b/src/utils/message.ts
index 8634e7d..1cb3a7a 100644
--- a/src/utils/message.ts
+++ b/src/utils/message.ts
@@ -17,6 +17,7 @@ const byteOptions: BytesOptions = {
   fixedDecimals: true,
   unitSeparator: " ",
 };
+const formatBytes = (byte: number) => bytes(byte, byteOptions) || "";
 
 export const getExtSizeChangeComment = async (
   currentSize: number,
@@ -29,17 +30,16 @@ export const getExtSizeChangeComment = async (
   return json2md([
     {
       collapsible: {
-        summary: `Extension Size Change: &nbsp ${bytes(
-          sizeDiff,
-          byteOptions
+        summary: `Extension Size Change: &nbsp ${formatBytes(
+          sizeDiff
         )} ${getEmoji(sizeDiff)}`,
         description: json2md({
           table: {
             headers: ["", ""],
             rows: [
               ["Commit", commitId],
-              ["Latest release size", bytes(latestReleaseSize, byteOptions)],
-              ["Current size", bytes(currentSize, byteOptions)],
+              ["Latest release size", formatBytes(latestReleaseSize)],
+              ["Current size", formatBytes(currentSize)],
               ["Percent change", `${percentChange.toFixed(2)} %`],
             ],
           },