diff --git a/gcc/config/vax/ultrix.h b/gcc/config/vax/ultrix.h
new file mode 100644
index 00000000000..9ed664a6752
--- /dev/null
+++ b/gcc/config/vax/ultrix.h
@@ -0,0 +1,13 @@
+#include "vax.h"
+
+#undef CPP_PREDEFINES
+#define CPP_PREDEFINES " -Dvax -Dunix -Dultrix -Dbsd4_2 -D__vax -D__unix -D__ultrix -D__bsd4_2"
+
+/* By default, allow $ to be part of an identifier.  */
+#define DOLLARS_IN_IDENTIFIERS 1
+
+/* These are as defined in /usr/include/sys/stdtypes.h */
+#define SIZE_TYPE "unsigned int"
+#define PTRDIFF_TYPE "int"
+#define WCHAR_TYPE "short unsigned int"
+#define WCHAR_TYPE_SIZE 16