diff --git a/config.mk b/config.mk
index 84525ce..4251cd6 100644
--- a/config.mk
+++ b/config.mk
@@ -10,7 +10,9 @@ LD = $(CC)
 AR = ar
 RANLIB = ranlib
 
-# For NetBSD add -D_NETBSD_SOURCE
+# for NetBSD add -D_NETBSD_SOURCE
+# for glibc on 32bit add -D_FILE_OFFSET_BITS=64 or use something sane
+# -lrt might be needed on some systems
 CPPFLAGS = -D_DEFAULT_SOURCE -D_BSD_SOURCE -D_XOPEN_SOURCE=700
 CFLAGS   = -std=c99 -Wall -pedantic
 LDFLAGS  = -s