diff --git a/Makefile b/Makefile
index e83fc0b..54f04b9 100644
--- a/Makefile
+++ b/Makefile
@@ -42,6 +42,7 @@
 endif
 ifeq ($(OS_ARCH), Darwin)
 CPPFLAGS += -I/opt/local/include -I/usr/local/include
+# DirectIO framework can be found in the DirectHW library.
 LDFLAGS += -framework IOKit -framework DirectIO -L/opt/local/lib -L/usr/local/lib
 endif
 ifeq ($(OS_ARCH), FreeBSD)