diff --git a/doc/Makefile b/doc/Makefile
index d5a37da..75fc6e6 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -7,8 +7,10 @@ clean:
 
 html/%.html: %.txt
 	mkdir html 2> /dev/null || true
-	( echo "<!doctype html>"; \
-	  echo "<link rel="stylesheet" href="http://c9x.me/css/simple.css" type="text/css" />"; \
+	( echo '<!doctype html>'; \
+	  echo '<link rel="stylesheet"' \
+	  	'href="http://c9x.me/css/simple.css"' \
+	  	'type="text/css" />'; \
 	  echo '<div class="container">'; \
 	  sed -ne '2{s,.*,<h2>&</h2>,;p;q}' $<; \
 	  sed -e '1,3d' $< | ocaml txt.ml; \
