diff --git a/src/m/iris4d.h b/src/m/iris4d.h
index bd374367375..04b85467b7f 100644
--- a/src/m/iris4d.h
+++ b/src/m/iris4d.h
@@ -143,7 +143,7 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 
 /* When you *do* link with -lbsd, you *still* get System V getpgrp, unless:
    you define _BSD_COMPAT, -or- you call `BSDgetpgrp' explicitly.
-   Emacs does neither, so it gets SysV getpgrp which wants no arguments.  */
+   Emacs does the latter.  */
 
 #ifdef HAVE_CRTN
 /* Must define START-FILES so that the linker can find /usr/lib/crt0.o.  */
diff --git a/src/s/irix4-0.h b/src/s/irix4-0.h
index 05ad1d21552..70c255044db 100644
--- a/src/s/irix4-0.h
+++ b/src/s/irix4-0.h
@@ -3,6 +3,8 @@
 #define USG5_3
 #define IRIX4
 
+#define USE_IRIX_BSDPGRP
+
 #define HAVE_ALLOCA
 #ifndef NOT_C_CODE
 #include <alloca.h>
@@ -53,6 +55,3 @@
 /* jpff@maths.bath.ac.uk reports `struct exception' is not defined
    on this system, so inhibit use of matherr.  */
 #define NO_MATHERR
-
-/* Info from simon@lia.di.epfl.ch (Simon Leinen) suggests this is needed.  */
-#define GETPGRP_NO_ARG