diff --git a/src/execute.ts b/src/execute.ts
index 02caa011..92da0437 100644
--- a/src/execute.ts
+++ b/src/execute.ts
@@ -1,6 +1,7 @@
 import {exec} from '@actions/exec'
+import buffer from 'buffer'
 
-let output: string
+let output = ''
 
 /** Wrapper around the GitHub toolkit exec command which returns the output.
  * Also allows you to easily toggle the current working directory.
@@ -29,5 +30,7 @@ export async function execute(
 }
 
 export function stdout(data: any): string | void {
-  output += data.toString().trim()
+  if (output.length < buffer.constants.MAX_STRING_LENGTH) {
+    output += data.toString().trim()
+  }
 }