diff --git a/spec/std/file_spec.cr b/spec/std/file_spec.cr
index 074b7072125a..82c1ab991a8a 100644
--- a/spec/std/file_spec.cr
+++ b/spec/std/file_spec.cr
@@ -64,7 +64,7 @@ describe "File" do
 
       rbuf = Bytes.new(5120)
       wbuf = Bytes.new(5120)
-      Random::DEFAULT.random_bytes(wbuf)
+      Random::Secure.random_bytes(wbuf)
 
       File.open(path, "r") do |reader|
         # opened fifo for read: wait for thread to open for write