diff --git a/Custom-Commands-Compendium.md b/Custom-Commands-Compendium.md
index 3a2637c..24e2a93 100644
--- a/Custom-Commands-Compendium.md
+++ b/Custom-Commands-Compendium.md
@@ -4,7 +4,7 @@ If you want to know how to implement your own custom commands see [here](https:/
 
 ## Creating a review in [Gerrit](https://gerrit-review.googlesource.com/Documentation/intro-gerrit-walkthrough.html)
 
-```
+```yml
 customCommands:
   - key: '<c-p>'
     command: "git push origin HEAD:refs/for/{{.CheckedOutBranch.Name}}"
@@ -14,7 +14,7 @@ customCommands:
 
 ## Pushing to a specific remote branch
 
-```
+```yml
 customCommands:
   - key: '<c-p>'
     context: 'global'
@@ -26,7 +26,7 @@ customCommands:
 ```
 ## Creating an annotated tag
 
-```
+```yml
   - key : 'N'
     description: 'create annotated tag'
     command: "git tag -a {{index .PromptResponses 0}} -m \"{{index .PromptResponses 1}}\""
@@ -40,7 +40,7 @@ customCommands:
 
 ## Open GitHub Pull Request
 
-```
+```yml
 customCommands:
   - key: "<c-r>"
     command: "gh pr create --fill --web"
@@ -52,7 +52,7 @@ This can be customized to fit your needs. Run `gh pr create --help` to see what
 
 ## Checkout branch via Github Pull Request id
 
-```
+```yml
 customCommands:
   - key: "v" # couldn't think of a better keybinding
     prompts:
@@ -62,3 +62,13 @@ customCommands:
     context: "localBranches"
     loadingText: "checking out PR"
 ```
+
+## Opening git mergetool
+
+```yml
+  - key: "M"
+    command: "git mergetool {{ .SelectedFile.Name }}"
+    context: "files"
+    loadingText: "opening git mergetool"
+    subprocess: true
+```
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