diff --git a/functions/internals/views.ts b/functions/internals/views.ts
index 2f9b670..e5e4cca 100644
--- a/functions/internals/views.ts
+++ b/functions/internals/views.ts
@@ -997,7 +997,7 @@ interface reportStartBlocksArgs {
   blocks: AnyModalBlock[];
   isLifelogEnabled: boolean;
 }
-function reportStartBlocks(
+export function reportStartBlocks(
   { language, offset, blocks, isLifelogEnabled }: reportStartBlocksArgs,
 ) {
   const yyyymmdd = todayYYYYMMDD(offset);
@@ -1032,7 +1032,7 @@ function reportStartBlocks(
       value: i.toString(),
     });
   }
-  const month = yyyymmdd.substring(4, 6);
+  const month = Number.parseInt(yyyymmdd.substring(4, 6));
   blocks.push({
     "type": "input",
     "block_id": BlockId.Month,
@@ -1042,8 +1042,8 @@ function reportStartBlocks(
       "action_id": ActionId.Input,
       "options": months,
       "initial_option": {
-        text: { type: "plain_text", text: month },
-        value: month,
+        text: { type: "plain_text", text: month.toString() },
+        value: month.toString(),
       },
     },
   });
diff --git a/functions/internals/views_test.ts b/functions/internals/views_test.ts
new file mode 100644
index 0000000..4f49c46
--- /dev/null
+++ b/functions/internals/views_test.ts
@@ -0,0 +1,26 @@
+import { assertEquals } from "std/assert/assert_equals.ts";
+import { reportStartBlocks } from "./views.ts";
+import { LanguageCode } from "./constants.ts";
+import { AnyModalBlock } from "slack-web-api-client/index.ts";
+import { StaticSelect, ViewInputBlock } from "slack-web-api-client/mod.ts";
+
+Deno.test("reportStartBlocks", () => {
+  const blocks: AnyModalBlock[] = [];
+  reportStartBlocks({
+    language: LanguageCode.English,
+    offset: 0,
+    blocks,
+    isLifelogEnabled: true,
+  });
+  assertEquals(blocks.length, 3);
+  const year = (blocks[0] as ViewInputBlock).element as StaticSelect;
+  assertEquals(
+    year.options?.map((o) => o.value).includes(year.initial_option?.value),
+    true,
+  );
+  const month = (blocks[1] as ViewInputBlock).element as StaticSelect;
+  assertEquals(
+    month.options?.map((o) => o.value).includes(month.initial_option?.value),
+    true,
+  );
+});