diff --git a/src/m/ibmps2-aix.h b/src/m/ibmps2-aix.h
index 0e1b17db436..e69588c5589 100644
--- a/src/m/ibmps2-aix.h
+++ b/src/m/ibmps2-aix.h
@@ -123,7 +123,6 @@ so disable it for them.  */
 #endif
 
 #define BSTRING
-#define HAVE_DUP2
 #define HAVE_GETTIMEOFDAY
 #define HAVE_SELECT
 #define HAVE_TIMEVAL
diff --git a/src/m/ibmrs6000.h b/src/m/ibmrs6000.h
index 921a4cc0b23..f42cf14eedd 100644
--- a/src/m/ibmrs6000.h
+++ b/src/m/ibmrs6000.h
@@ -119,7 +119,6 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 #define C_SWITCH_MACHINE -D_BSD
 #define LIBS_MACHINE -lrts
 #define START_FILES
-#define HAVE_DUP2
 #define HAVE_GETTIMEOFDAY
 #define HAVE_SYSVIPC
 #define HAVE_SETSID
diff --git a/src/m/ibmrt-aix.h b/src/m/ibmrt-aix.h
index bca2969e9a1..2ec5919a280 100644
--- a/src/m/ibmrt-aix.h
+++ b/src/m/ibmrt-aix.h
@@ -168,7 +168,6 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 
 #include </usr/include/bsd/BSDtoAIX.h>
 #define BSTRING
-#define HAVE_DUP2
 #define HAVE_GETTIMEOFDAY
 #define HAVE_SELECT
 #define HAVE_TIMEVAL
diff --git a/src/m/mips.h b/src/m/mips.h
index bd4466ee9ba..6125fc88abd 100644
--- a/src/m/mips.h
+++ b/src/m/mips.h
@@ -221,7 +221,6 @@ NOTE-END  */
    The `select' in the system won't work for pipes,
    so don't use it.  */
 
-#define HAVE_DUP2
 #define HAVE_GETWD
 #define HAVE_GETTIMEOFDAY
 
diff --git a/src/m/sps7.h b/src/m/sps7.h
index 95c106ac133..5e838592cc6 100644
--- a/src/m/sps7.h
+++ b/src/m/sps7.h
@@ -119,10 +119,6 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
   
 #undef SIGIO
 
-/* Some additional system facilities exist.  */
-
-#define HAVE_DUP2
-
 /* Other than 68020 use ld16, as32, or undefine (defaults ld and as). */
 
 #define ASS as32
diff --git a/src/s/aix3-1.h b/src/s/aix3-1.h
index e4a4612a67a..f75518675d6 100644
--- a/src/s/aix3-1.h
+++ b/src/s/aix3-1.h
@@ -231,8 +231,5 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 
 #define SYSTEM_MALLOC
 
-/* Use the gethostname system call.  */
-#define HAVE_GETHOSTNAME
-
 /* AIX doesn't define this.  */
 #define unix 1
diff --git a/src/s/hpux.h b/src/s/hpux.h
index ce40e6e3ca7..fb3903d96e6 100644
--- a/src/s/hpux.h
+++ b/src/s/hpux.h
@@ -224,12 +224,8 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 
 /* Some additional system facilities exist.  */
 
-#define HAVE_DUP2
 #define HAVE_GETTIMEOFDAY
 
-/* Implementation of uname is broken on hpux.  Use gethostname.  */
-#define HAVE_GETHOSTNAME
-
 #define HAVE_VFORK
 #define HAVE_PERROR  /* Delete this line for version 6.  */
 #define HAVE_RENAME
diff --git a/src/s/irix3-3.h b/src/s/irix3-3.h
index 004873cf9df..42d6d9d8f62 100644
--- a/src/s/irix3-3.h
+++ b/src/s/irix3-3.h
@@ -179,6 +179,3 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 
 /* Use setsid to handle terminals for subprocesses.  */
 #define HAVE_SETSID
-
-/* Implementation of uname is broken on Irix as of version 3.3 */
-#define HAVE_GETHOSTNAME