--- a/configure.in
+++ b/configure.in
@@ -24,7 +24,7 @@ if test "$LUSB" = "no"; then
   echo "   http://libusb.sourceforge.net"
   echo "   or use the --with-libusb-includes option, if you have it installed"
   echo "   in an unusual place"
-  exit
+  exit 1
 fi
 AC_CHECK_LIB(usb, usb_init, LUSB="yes", LUSB="no")
 if test "$LUSB" = "no"; then
@@ -33,7 +33,7 @@ if test "$LUSB" = "no"; then
   echo "   http://libusb.sourceforge.net"
   echo "   or use the --with-libusb-libraries option, if you have it installed"
   echo "   in an unusual place"
-  exit
+  exit 1
 fi
 
 AC_OUTPUT(Makefile)