diff --git a/subaction/matrix-targets/action.yml b/subaction/matrix-targets/action.yml
index acc5cb9..8a99858 100644
--- a/subaction/matrix-targets/action.yml
+++ b/subaction/matrix-targets/action.yml
@@ -53,10 +53,7 @@ runs:
           });
 
           await core.group(`Set matrix`, async () => {
-            let matrix = [];
-            for (const [key, value] of Object.entries(def.target)) {
-              matrix.push(key);
-            }
+            const matrix = Object.keys(def.target);
             core.info(`matrix: ${JSON.stringify(matrix)}`);
             core.setOutput('matrix', JSON.stringify(matrix));
           });