--- a/Makefile	
+++ a/Makefile	
@@ -42,6 +42,9 @@ CFLAGS=-O2 $(WARNINGS)
 ifeq ($(uname_S),Linux)
  DEFINES=-DAUTOCONF -DPOSIX -DUSG -D_BSD_SOURCE -D_SVID_SOURCE -D_XOPEN_SOURCE=600
 endif
+ifeq ($(uname_S),FreeBSD)
+ DEFINES=-DAUTOCONF -DPOSIX -DSYSV -D_FREEBSD_C_SOURCE -D_BSD_SOURCE -D_SVID_SOURCE -D_XOPEN_SOURCE=600
+endif
 ifeq ($(uname_S),Darwin)
  DEFINES=-DAUTOCONF -DPOSIX -DSYSV -D_DARWIN_C_SOURCE -D_BSD_SOURCE -D_SVID_SOURCE -D_XOPEN_SOURCE=600
 endif
--- a/posix.c	
+++ a/posix.c	
@@ -25,7 +25,7 @@ 
 
 /* Since Mac OS X's termios.h doesn't have the following 2 macros, define them.
  */
-#if defined(SYSV) && defined(_DARWIN_C_SOURCE)
+#if defined(SYSV) && (defined(_DARWIN_C_SOURCE) || defined(_FREEBSD_C_SOURCE))
 #define OLCUC 0000002
 #define XCASE 0000004
 #endif