diff --git a/autogen/configure b/autogen/configure
index 14437b168b1..471ac175b0e 100755
--- a/autogen/configure
+++ b/autogen/configure
@@ -15521,6 +15521,12 @@ case $opsys in
 
     ;;
 
+  aix*)
+        $as_echo "#define DATA_START 0x20000000" >>confdefs.h
+
+    $as_echo "#define DATA_SEG_BITS 0x20000000" >>confdefs.h
+
+    ;;
   hpux*)
         $as_echo "#define DATA_START 0x40000000" >>confdefs.h
 
@@ -15615,7 +15621,7 @@ esac
 
 
 case $opsys in
-  aix4-2 | hpux* | unixware)
+  hpux* | unixware)
             $as_echo "#define GC_MARK_STACK GC_USE_GCPROS_AS_BEFORE" >>confdefs.h
 
     ;;