--- AltairZ80/i86_ops.c.orig	Thu Feb 18 15:22:11 2021
+++ AltairZ80/i86_ops.c	Thu Feb 18 15:22:29 2021
@@ -110,6 +110,8 @@
 
 extern uint8 parity_tab[];
 
+extern volatile int intr;
+
 static void i86op_illegal_op(PC_ENV *m)
 {
     intr |= INTR_ILLEGAL_OPCODE;