diff --git a/index.js b/index.js
index 06444bf..0437a4b 100644
--- a/index.js
+++ b/index.js
@@ -5,7 +5,7 @@ const fs = require("fs")
 var { benchBranch, benchmarkRuntime } = require("./bench");
 
 module.exports = app => {
-  const baseBranch = process.env.BASE_BRANCH || "master" 
+  const baseBranch = process.env.BASE_BRANCH || "master"
   app.log(`base branch: ${baseBranch}`);
 
   const appId = parseInt(process.env.APP_ID)
@@ -93,6 +93,9 @@ module.exports = app => {
       report = await benchBranch(app, config)
     };
 
+    // Max github body is 65536 characters... we are a little conservative.
+    report = report.substring(0, 65000)
+
     if (report.error) {
       app.log(`error: ${report.stderr}`)
       if (report.step != "merge") {