diff --git a/tox.ini b/tox.ini
index 9da0b22..04f0fd8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -21,7 +21,7 @@ wheel_build_env = .pkg
 deps =
     pytest>=6
 setenv =
-    ; NB: You may need to copy build/fdb5/etc/fdb to build/etc/fdb
-    FDB_HOME=../build/
+    ; FDB_HOME=../build/fdb5 # FDB_HOME specifies a folder that contains etc/fdb/config.yaml
+    FDB5_HOME=../build/ # FDB5_HOME specifies the library location, i.e. a folder that contains lib/libfdb5.dylib
 commands =
     pytest {tty:--color=yes} {posargs}