diff --git a/book/source/mermaid/09-sigtree.md b/book/input/09-sigtree.md
similarity index 100%
rename from book/source/mermaid/09-sigtree.md
rename to book/input/09-sigtree.md
diff --git a/book/source/09-verification.md b/book/source/09-verification.md
index 22c731f..059c48d 100644
--- a/book/source/09-verification.md
+++ b/book/source/09-verification.md
@@ -73,7 +73,9 @@ This construct is referred to as a [revocation certificate](https://www.ietf.org
 
 On the other hand, in order to verify a data signature over a text document, an implementation would need to verify not only the data signature itself, but also the binding signature (and back-signature) of the signing subkey, which qualify the signing subkey.
 
-```{include} mermaid/09-sigtree.md
+```{figure} mermaid/09-sigtree.png
+
+Tree of signatures
 ```
 
 ### Attribute shadowing
diff --git a/book/source/mermaid/09-sigtree.png b/book/source/mermaid/09-sigtree.png
new file mode 100644
index 0000000..dc35f65
Binary files /dev/null and b/book/source/mermaid/09-sigtree.png differ