diff --git a/jtag/configure.ac b/jtag/configure.ac
index 5c4d7549..cd967e0b 100644
--- a/jtag/configure.ac
+++ b/jtag/configure.ac
@@ -99,27 +99,31 @@ AC_CHECK_HEADERS(linux/ppdev.h)
 VL_LIB_READLINE
 
 dnl check for libftdi-config
-AC_PATH_PROG(HAVELIBFTDI, libftdi-config, $PATH)
-if test ! -z "$HAVELIBFTDI"; then
+AC_PATH_PROG(HAVELIBFTDI, libftdi-config, no)
+if test "$HAVELIBFTDI" != "no" ; then
 dnl   LIBFTDI_CFLAGS=`$HAVELIBFTDI --cflags`
+   AM_CONDITIONAL(HAVE_LIBFTDI, true)
    LIBFTDI_LIBS=`$HAVELIBFTDI --libs`
    CFLAGS="$CFLAGS $LIBFTDI_CFLAGS"
    LIBS="$LIBS $LIBFTDI_LIBS"
    AC_DEFINE(HAVE_LIBFTDI, 1, [Define if you have libftdi])
 else
-   AC_MSG_ERROR([*** libftdi-config not found. You need a working libftdi installation.])
+   AM_CONDITIONAL(HAVE_LIBFTDI, false)
+   AC_MSG_WARN([*** libftdi-config not found. No support for FTDI-based USB JTAG cables.])
 fi
 
 dnl check for libusb-config
-AC_PATH_PROG(HAVELIBUSB, libusb-config, $PATH)
-if test ! -z "$HAVELIBUSB"; then
+AC_PATH_PROG(HAVELIBUSB, libusb-config, no) 
+if test "$HAVELIBUSB" != "no" ; then
 dnl   LIBUSB_CFLAGS=`$HAVELIBUSB --cflags`
+   AM_CONDITIONAL(HAVE_LIBUSB, true)
    LIBUSB_LIBS=`$HAVELIBUSB --libs`
    CFLAGS="$CFLAGS $LIBUSB_CFLAGS"
    LIBS="$LIBS $LIBUSB_LIBS"
    AC_DEFINE(HAVE_LIBUSB, 1, [Define if you have libusb])
 else
-   AC_MSG_ERROR([*** libusb-config not found. You need a working libusb installation.])
+   AM_CONDITIONAL(HAVE_LIBUSB, false)
+   AC_MSG_WARN([*** libusb-config not found. Omitting support for some USB JTAG cables.])
 fi
 
 CFLAGS="$CFLAGS -Wall"
diff --git a/jtag/src/tap/Makefile.am b/jtag/src/tap/Makefile.am
index c8f809f9..6445564f 100644
--- a/jtag/src/tap/Makefile.am
+++ b/jtag/src/tap/Makefile.am
@@ -33,17 +33,12 @@ libtap_a_SOURCES = \
 	parport.c \
 	parport/direct.c \
 	parport/ppdev.c \
-    parport/xpcu_common.c \
-    parport/xpcu_pp.c \
-	parport/ftdi.c \
 	cable.c \
 	cable/generic.h \
 	cable/generic.c \
 	cable/arcom.c \
 	cable/byteblaster.c \
-	cable/usbblaster.c \
 	cable/dlc5.c \
-    cable/xpc.c \
 	cable/ea253.c \
 	cable/ei012.c \
 	cable/keithkoep.c \
@@ -52,3 +47,17 @@ libtap_a_SOURCES = \
 	cable/triton.c \
 	cable/wiggler.c \
 	cable/wiggler2.c
+
+if HAVE_LIBUSB
+libtap_a_SOURCES += \
+	parport/xpcu_common.c \
+	parport/xpcu_pp.c \
+	cable/xpc.c
+endif
+
+if HAVE_LIBFTDI
+libtap_a_SOURCES += \
+	parport/ftdi.c \
+	cable/usbblaster.c
+endif
+
diff --git a/jtag/src/tap/cable.c b/jtag/src/tap/cable.c
index 75bdac87..6ce644a7 100644
--- a/jtag/src/tap/cable.c
+++ b/jtag/src/tap/cable.c
@@ -37,7 +37,9 @@
 
 extern cable_driver_t arcom_cable_driver;
 extern cable_driver_t byteblaster_cable_driver;
+#ifdef HAVE_LIBFTDI
 extern cable_driver_t usbblaster_cable_driver;
+#endif
 extern cable_driver_t dlc5_cable_driver;
 extern cable_driver_t ea253_cable_driver;
 extern cable_driver_t ei012_cable_driver;
@@ -57,7 +59,9 @@ extern cable_driver_t xpc_ext_cable_driver;
 cable_driver_t *cable_drivers[] = {
 	&arcom_cable_driver,
 	&byteblaster_cable_driver,
+#ifdef HAVE_LIBFTDI
 	&usbblaster_cable_driver,
+#endif
 	&dlc5_cable_driver,
 	&ea253_cable_driver,
 	&ei012_cable_driver,