diff --git a/ext/mbstring/config.m4 b/ext/mbstring/config.m4
index 3465021e17f..8c9246f6d6a 100644
--- a/ext/mbstring/config.m4
+++ b/ext/mbstring/config.m4
@@ -87,7 +87,7 @@ esac
 )
     ])
 
-    AC_CHECK_HEADERS([stdlib.h string.h strings.h unistd.h sys/time.h sys/times.h])
+    AC_CHECK_HEADERS([stdlib.h string.h strings.h unistd.h sys/time.h sys/times.h stdarg.h])
     AC_CHECK_SIZEOF(int, 4)
     AC_CHECK_SIZEOF(short, 2)
     AC_CHECK_SIZEOF(long, 4)
@@ -96,9 +96,6 @@ esac
     AC_FUNC_ALLOCA
     AC_FUNC_MEMCMP
 
-    if test "$cv_php_mbstring_stdarg" = "yes"; then
-      AC_DEFINE([HAVE_STDARG_PROTOTYPES], 1, [Define if stdarg.h is available])
-    fi
     AC_DEFINE([HAVE_MBREGEX], 1, [whether to have multibyte regex support])
 
 
diff --git a/ext/mbstring/oniguruma/php_onig_compat.h b/ext/mbstring/oniguruma/php_onig_compat.h
index 1de0d6073dc..94ece40ef21 100644
--- a/ext/mbstring/oniguruma/php_onig_compat.h
+++ b/ext/mbstring/oniguruma/php_onig_compat.h
@@ -5,4 +5,10 @@
 #define regex_t                     php_mb_regex_t
 #define re_registers                php_mb_re_registers
 
+#ifdef HAVE_STDARG_H
+#ifndef HAVE_STDARG_PROTOTYPES
+#define HAVE_STDARG_PROTOTYPES 1
+#endif
+#endif
+
 #endif /* _PHP_MBREGEX_COMPAT_H */