diff --git a/src/m/ibmrs6000.h b/src/m/ibmrs6000.h
index d0f9fdf0f9e..135ef516eed 100644
--- a/src/m/ibmrs6000.h
+++ b/src/m/ibmrs6000.h
@@ -132,3 +132,7 @@ the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
 
 #define ORDINARY_LINK
 #define LD_SWITCH_MACHINE -Wl,-bnso,-bnodelcsect,-bI:/lib/syscalls.exp
+
+/* AIX supposedly doesn't use this interface, but on thr RS/6000
+   it apparently does.  */
+#define NLIST_STRUCT