diff --git a/src/actions-util.ts b/src/actions-util.ts
index 2038be98a..952ddcd3f 100644
--- a/src/actions-util.ts
+++ b/src/actions-util.ts
@@ -887,7 +887,7 @@ export async function uploadDebugArtifacts(
   }
   let suffix = "";
   const matrix = getRequiredInput("matrix");
-  if (matrix !== undefined && matrix !== "null") {
+  if (matrix) {
     for (const entry of Object.entries(JSON.parse(matrix)).sort())
       suffix += `-${entry[1]}`;
   }