diff --git a/gcc/ginclude/stdarg.h b/gcc/ginclude/stdarg.h
index 2101867f723..33dd5ece3cc 100644
--- a/gcc/ginclude/stdarg.h
+++ b/gcc/ginclude/stdarg.h
@@ -42,7 +42,7 @@
 
 #ifndef __GNUC_VA_LIST
 #define __GNUC_VA_LIST
-#ifdef __svr4__
+#if defined(__svr4__) || defined(_AIX) || defined(_M_UNIX)
 typedef char *__gnuc_va_list;
 #else
 typedef void *__gnuc_va_list;
diff --git a/gcc/ginclude/varargs.h b/gcc/ginclude/varargs.h
index ef2eeaffa10..9af23e9b183 100644
--- a/gcc/ginclude/varargs.h
+++ b/gcc/ginclude/varargs.h
@@ -73,7 +73,7 @@
 
 #ifndef __GNUC_VA_LIST
 #define __GNUC_VA_LIST
-#ifdef __svr4__
+#if defined(__svr4__) || defined(_AIX) || defined(_M_UNIX)
 typedef char *__gnuc_va_list;
 #else
 typedef void *__gnuc_va_list;