Allow making update with no prior checkout.
diff --git a/Doc/Makefile b/Doc/Makefile
index d26117b..d2a0806 100644
--- a/Doc/Makefile
+++ b/Doc/Makefile
@@ -32,7 +32,7 @@
 	  svn checkout $(SVNROOT)/external/Pygments-0.8.1/pygments tools/pygments; \
 	fi
 
-update:
+update: checkout
 	svn update tools/sphinx
 	svn update tools/docutils
 	svn update tools/pygments