diff -up ATLAS/CONFIG/src/probe_comp.c.s390 ATLAS/CONFIG/src/probe_comp.c
--- ATLAS/CONFIG/src/probe_comp.c.s390	2009-12-10 13:18:24.000000000 +0100
+++ ATLAS/CONFIG/src/probe_comp.c	2009-12-10 13:19:17.000000000 +0100
@@ -535,7 +535,11 @@ char *GetPtrbitsFlag(enum OSTYPE OS, enu
    else if (ptrbits == 64)
      sp = "-m64";
    else if (ptrbits == 32)
+#ifdef __s390__
+     sp = "-m31";
+#else
      sp = "-m32";
+#endif
    return(sp);
 }
 char *GetStandardCompName(char *comp)
diff -up ATLAS/CONFIG/src/SpewMakeInc.c.s390 ATLAS/CONFIG/src/SpewMakeInc.c
--- ATLAS/CONFIG/src/SpewMakeInc.c.s390	2009-12-10 13:22:16.000000000 +0100
+++ ATLAS/CONFIG/src/SpewMakeInc.c	2009-12-10 13:22:19.000000000 +0100
@@ -368,7 +368,11 @@ char *GetPtrbitsFlag(enum OSTYPE OS, enu
    else if (ptrbits == 64)
      sp = "-m64";
    else if (ptrbits == 32)
+#ifdef __s390__
+     sp = "-m31";
+#else
      sp = "-m32";
+#endif
    return(sp);
 }