diff --git a/src/syncterm/GNUmakefile b/src/syncterm/GNUmakefile
index 785f9dcacd81f150b998f7b4ac367d6310f98a54..b1bf753fff2dad43164fb95b040630192fdd85f3 100644
--- a/src/syncterm/GNUmakefile
+++ b/src/syncterm/GNUmakefile
@@ -1,6 +1,8 @@
 SRC_ROOT	:=	..
 include ${SRC_ROOT}/build/Common.gmake
 
+CFLAGS	+=	-I/usr/local/include	# cryptlib.h lives here by default
+
 ifeq ($(os),sunos)    # Solaris
  LDFLAGS += -lnsl -lrt -lcurses -ldl
  CFLAGS	+=	-DNEED_CFMAKERAW
@@ -11,6 +13,10 @@ ifdef USE_GUTS
  OBJS	+=	$(MTOBJODIR)$(DIRSEP)gutsz$(OFILE)
 endif
 
+ifdef PREFIX
+ CFLAGS	+=	-DPREFIX=\"${PREFIX}\"
+endif
+
 CFLAGS	+=	$(UIFC-MT_CFLAGS) $(CIOLIB-MT_CFLAGS) $(XPDEV-MT_CFLAGS) -I../sbbs3 -I../smblib
 LDFLAGS	+=	$(UIFC-MT_LDFLAGS) $(CIOLIB-MT_LDFLAGS) $(XPDEV-MT_LDFLAGS)