diff --git a/src/Runner.Worker/ActionManifestManager.cs b/src/Runner.Worker/ActionManifestManager.cs
index 759cd36ff..80a805035 100644
--- a/src/Runner.Worker/ActionManifestManager.cs
+++ b/src/Runner.Worker/ActionManifestManager.cs
@@ -75,7 +75,7 @@ namespace GitHub.Runner.Worker
 
                 // Add this file to the FileTable in executionContext if it hasn't been added already
                 // we use > since fileID is 1 indexed
-                if (fileId > executionContext.FileTable.Count)
+                if (fileId > executionContext.FileTable?.Count)
                 {
                     executionContext.FileTable.Add(fileRelativePath);
                 }