diff --git a/slides/Makefile b/slides/Makefile
index 08a369244ec1ae32d7c60840e09f1c49d915640b..de9d4717e223e04b096e18707943468bc243f3bd 100644
--- a/slides/Makefile
+++ b/slides/Makefile
@@ -33,10 +33,10 @@ markdown: $(MARKDOWN) # La markdown les cibles %.markdown
 	pandoc -s $(OPTIONS) $(REVEALOPTIONS) -o $@ $^
 
 %.markdown: metadata.yaml %.md yq
-	sed '1 { /^---/ { :a N; /\n---/! ba; d} }' $< > no_header
-	grep -v -F -x -f  no_header $< > header.yaml
+	sed '1 { /^---/ { :a N; /\n---/! ba; d} }' $(shell echo $(word 2, $^)) > no_header
+	grep -v -F -x -f  no_header $(shell echo $(word 2, $^)) > header.yaml
 	echo "---" > tmp.yaml
-	./yq_linux_amd64 merge metadata.yaml header.yaml >> tmp.yaml
+	./yq_linux_amd64 merge header.yaml metadata.yaml >> tmp.yaml
 	cat tmp.yaml no_header > $@
 	rm no_header header.yaml tmp.yaml
 
diff --git a/slides/intro.md b/slides/intro.md
index 88282e279c565dc1a1d4933088a043f56ad8ce2a..a7d13e17af41708f563f94a86f3d6d2d51fe2d1d 100644
--- a/slides/intro.md
+++ b/slides/intro.md
@@ -6,7 +6,7 @@ patat:
     margins:
         left: 10
         right: 10
-...
+---
 
 # La hotline
 
diff --git a/slides/metadata.yaml b/slides/metadata.yaml
index 13a7a5e195c8f7814bac137dfa247ba2ab400e81..fe0a4d5ed53f4a73bd656b39eda35ea8a68da72e 100644
--- a/slides/metadata.yaml
+++ b/slides/metadata.yaml
@@ -1,8 +1,8 @@
 ---
 subtitle: "Programmation séquentielle en C, 2021-2022"
 author: "Orestis Malaspinas (A401), ISC, HEPIA"
-institute: Inspirés des slides de F. Glück
-lang: fr-CH
+institute: "Inspirés des slides de F. Glück"
+lang: "fr-CH"
 revealjs-url: /reveal.js
 mathjaxurl: "https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.0/MathJax.js?config=TeX-AMS_HTML"
 ---