diff --git a/CHANGELOG.md b/CHANGELOG.md
index 75802af4..b6ebba0b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 Version 187:
 
 * Add experimental timeout_socket
+* Fix warning in file tests
 
 --------------------------------------------------------------------------------
 
diff --git a/test/beast/core/file_test.hpp b/test/beast/core/file_test.hpp
index 49cd3d1d..510d6f1f 100644
--- a/test/beast/core/file_test.hpp
+++ b/test/beast/core/file_test.hpp
@@ -68,11 +68,13 @@ doTestFile(beast::unit_test::suite& test)
     test.BEAST_EXPECT(ec == errc::invalid_argument);
     ec.assign(0, ec.category());
 
-    f.read(nullptr, 0, ec);
+    char tmp[1];
+
+    f.read(tmp, 0, ec);
     test.BEAST_EXPECT(ec == errc::invalid_argument);
     ec.assign(0, ec.category());
 
-    f.write(nullptr, 0, ec);
+    f.write(tmp, 0, ec);
     test.BEAST_EXPECT(ec == errc::invalid_argument);
     ec.assign(0, ec.category());