diff --git a/src/slackAppHome.js b/src/slackAppHome.js
index 2a204cf..67e533e 100644
--- a/src/slackAppHome.js
+++ b/src/slackAppHome.js
@@ -100,9 +100,14 @@ function categorizePayments(payments) {
 // --- Main handler ---
 
 export const handler = async (event) => {
+  // Decode body — API Gateway may base64-encode it
+  let rawBody = event.body || "";
+  if (event.isBase64Encoded) {
+    rawBody = Buffer.from(rawBody, "base64").toString("utf-8");
+  }
+
   // Slack sends block_actions as form-encoded: payload=<JSON>
   let body;
-  const rawBody = event.body || "";
   if (rawBody.startsWith("payload=")) {
     body = JSON.parse(decodeURIComponent(rawBody.replace("payload=", "")));
   } else {