diff --git a/Formula/qpm.rb b/Formula/qpm.rb
index 1c83d41e98..0ac7c09084 100644
--- a/Formula/qpm.rb
+++ b/Formula/qpm.rb
@@ -50,6 +50,6 @@ class Qpm < Formula
 
   test do
     system bin/"qpm", "install", "io.qpm.example"
-    assert File.exist?(testpath/"qpm.json")
+    assert_predicate testpath/"qpm.json", :exist?
   end
 end