Index: channels/chan_zap.c
===================================================================
--- channels/chan_zap.c	(revision 9084)
+++ channels/chan_zap.c	(working copy)
@@ -105,6 +105,9 @@
 #ifndef ZT_SIG_EM_E1
 #error "Your zaptel is too old.  please update"
 #endif
+#ifndef ZT_SIG_HARDHDLC
+#error "Your zaptel is too old.  please update"
+#endif
 
 #ifndef ZT_TONEDETECT
 /* Work around older code with no tone detect */