diff --git a/examples/asm/functional_test/README.md b/examples/asm/functional_test/README.md
index 9c7dafc..ad31b85 100644
--- a/examples/asm/functional_test/README.md
+++ b/examples/asm/functional_test/README.md
@@ -1 +1,14 @@
-From https://github.com/Klaus2m5/6502_65C02_functional_tests
\ No newline at end of file
+# 6502 Functional Test
+
+This binary was taken from
+https://github.com/Klaus2m5/6502_65C02_functional_tests
+Copyright (C) 2013  Klaus Dormann
+
+This is a test suite for 6502/65C02/65C816 processors. It contains a plethora of
+tests, which covers all documented opcodes.
+
+Note that the binary was not built from the source code in the repository, but
+pre-built binaries were used instead. That is because the source code is not
+compatible with the assembler used by the [cc65](https://cc65.github.io/cc65/)
+toolchain.
+