--- media-libs/libdvbpsi/libdvbpsi-0.1.5.ebuild	2007-05-16 18:05:51.000000000 +0000
+++ local/media-libs/libdvbpsi/libdvbpsi-0.1.5.ebuild	2007-05-16 22:16:06.000000000 +0000
@@ -27,9 +27,19 @@
 	emake || die "emake failed"
 
 	if use doc; then
+		# Making the documentation requires that /usr/bin/dot from
+		# media-libs/graphviz supports PNG output.  According to bug #181147,
+		# this is not always enabled.  Check that /usr/bin/dot supports
+		# rendering to PNG before we try to make doc.  The -Txxx is picked to
+		# force an error from dot so that we can check what formats it supports.
+		if /usr/bin/dot -Txxx 2>&1 | grep -q png ; then
 		ewarn "Attempting to build documentation"
 		make doc || die "Could not build documentation."
 	else
+			ewarn "Building documentation requires PNG support in graphviz."
+		fi
+	else
 		ewarn "Documentation was not built"
 	fi
 }