diff --git a/doc/makefile b/doc/makefile
index d505dedf2..27df27587 100644
--- a/doc/makefile
+++ b/doc/makefile
@@ -9,7 +9,7 @@ all: gtk-sharp-docs.zip gtk-sharp-docs.tree
 b:
 	mono --debug $(BROWSER)
 
-gtk-sharp-docs.zip gtk-sharp-docs.tree:
+gtk-sharp-docs.zip gtk-sharp-docs.tree: en/*/*.xml
 	mono $(ASSEMBLER) --ecma en -o gtk-sharp-docs
 
 install: gtk-sharp-docs.zip gtk-sharp-docs.tree