diff --git a/src/s/aix4-1.h b/src/s/aix4-1.h
index 8d62582dd32..21b70a5124e 100644
--- a/src/s/aix4-1.h
+++ b/src/s/aix4-1.h
@@ -1,3 +1,6 @@
 #define AIX4_1 
 
 #include "aix4.h"
+
+/* Tomotake FURUHATA <furuhata@trl.ibm.co.jp> says this is needed.  */
+#define SYSTEM_MALLOC