diff --git a/acinclude.m4 b/acinclude.m4
index 4115c2f48..cfc1f07d1 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -495,6 +495,7 @@ AC_DEFUN([GB_SYSTEM],
     *-*-darwin* | *-*-rhapsody* )
       SYSTEM=MACOSX
       AC_DEFINE(OS_BSD, 1, [Target system is of BSD family])
+      AC_DEFINE(OS_FREEBSD, 1, [Target system is FreeBSD])
       AC_DEFINE(OS_MACOSX, 1, [Target system is MacOS X])
       AC_DEFINE(SYSTEM, "MacOSX", [Operating system])
       ;;
@@ -510,6 +511,12 @@ AC_DEFUN([GB_SYSTEM],
       AC_DEFINE(OS_KFREEBSD, 1, [Target system is kFREEBSD])
       AC_DEFINE(SYSTEM, "kFreeBSD", [Operating system])
       ;;
+    *-gnu* )
+      SYSTEM=HURD
+      AC_DEFINE(OS_GNU, 1, [Target system is of GNU family])
+      AC_DEFINE(OS_HURD, 1, [Target system is Hurd])
+      AC_DEFINE(SYSTEM, "Hurd", [Operating system])
+      ;;
     * )
       SYSTEM=UNKNOWN
       AC_DEFINE(SYSTEM, "unknown", [Operating system])
diff --git a/gb.net/src/CSerialPort.c b/gb.net/src/CSerialPort.c
index b339524ce..c17f4bb9e 100644
--- a/gb.net/src/CSerialPort.c
+++ b/gb.net/src/CSerialPort.c
@@ -38,6 +38,10 @@
 #define TIOCOUTQ ((unsigned int) -1)
 #endif /* __CYGWIN__ */
 
+#ifndef TIOCINQ
+#define TIOCINQ FIONREAD
+#endif
+
 #include "main.h"
 #include "tools.h"
 
diff --git a/main/share/gb_common.h b/main/share/gb_common.h
index 69c38e217..cf1b751e3 100644
--- a/main/share/gb_common.h
+++ b/main/share/gb_common.h
@@ -53,10 +53,6 @@
 #include <sys/param.h>
 #include <limits.h>
 
-#ifdef OS_MACOSX
-#define OS_FREEBSD
-#endif
-
 #if defined(__GNU_LIBRARY__) || defined(OS_FREEBSD)
 
 #include <getopt.h>
@@ -147,6 +143,14 @@ typedef
 #define LLONG_MAX 9223372036854775807LL
 #endif
 
+#ifndef PATH_MAX
+#define PATH_MAX 4096
+#endif
+
+#ifndef MAXPATHLEN
+#define MAXPATHLEN 4096
+#endif
+
 #define CLEAR(s) (memset(s, 0, sizeof(*s)))
 
 /* Workaround spurious gcc warnings */