diff --git a/README.md b/README.md
index f0d723b..697c004 100644
--- a/README.md
+++ b/README.md
@@ -7,3 +7,19 @@ This action uses [Talisman](https://thoughtworks.github.io/talisman/) to scan th
 ```yml
 uses: carhartl/talisman-secrets-scan-action@v1
 ```
+
+## Caveat
+
+When using this along with the `actions/checkout@v2` step, you'll need to configure it to fetch the entire history:
+
+```yml
+- uses: actions/checkout@v2
+  with:
+    fetch-depth: 0
+```
+
+Otherwise you'll run into talisman erroring out while it's trying to execute git with an invalid revision range:
+
+```
+time="2021-09-19T07:07:32Z" level=fatal msg="Git command execution failed" command="git diff 0c4a631e70056a95df1c235d238a80828e07cf9c..a32a5c7e1a3d250bf18a080a44a764d9b93b9690 --name-only --diff-filter=ACM" dir=/github/workspace error="exit status 128" output="fatal: Invalid revision range 0c4a631e70056a95df1c235d238a80828e07cf9c..a32a5c7e1a3d250bf18a080a44a764d9b93b9690\n"
+```