--- configure.in.old	2006-12-30 18:56:40.000000000 +0100
+++ configure.in	2006-12-30 19:06:20.000000000 +0100
@@ -349,7 +349,17 @@
 
 dnl gsf-sharp
 
-PKG_CHECK_MODULES(GSF_SHARP, gsf-sharp >= 0.5, enable_gsf_sharp=yes, enable_gsf_sharp=no)
+AC_ARG_ENABLE([gsf-sharp],
+	[],
+	 enable_gsf_sharp=$enableval,
+	 enable_gsf_sharp=auto)
+PKG_CHECK_MODULES(GSF_SHARP, gsf-sharp >= 0.5, has_gsf_sharp=yes, has_gsf_sharp=no)
+if test "x$has_gsf_sharp" = "xno"; then
+	if test "x$enable_gsf_sharp" = "xyes"; then
+		AC_MSG_ERROR([gsf-sharp >= 0.5 not found])
+		enable_gsf_sharp="no"
+	fi
+fi
 AM_CONDITIONAL(ENABLE_GSF_SHARP, test "x$enable_gsf_sharp" = "xyes")
 if test "x$enable_gsf_sharp" = "xyes"; then
 	BEAGLE_DEFINES="$BEAGLE_DEFINES -define:ENABLE_GSF_SHARP"