--- ghostscript-9.18.old/psi/ierrors.h
+++ ghostscript-9.18/psi/ierrors.h
@@ -21,6 +21,10 @@
 
 #include "gserrors.h"
 
+#define e_ExecStackUnderflow gs_error_ExecStackUnderflow
+#define e_Fatal gs_error_Fatal
+#define e_NeedInput gs_error_NeedInput
+
 /*
  * DO NOT USE THIS FILE IN THE GRAPHICS LIBRARY.
  * THIS FILE IS PART OF THE POSTSCRIPT INTERPRETER.