diff --git a/src/3rdparty/squirrel/README.OpenTTD b/src/3rdparty/squirrel/README.OpenTTD
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--- /dev/null
+++ b/src/3rdparty/squirrel/README.OpenTTD
@@ -0,0 +1,4 @@
+This folder contains a modified version of Squirrel that is tailored to meet
+the needs of OpenTTD.
+We have based this modification on the version as described in:
+include/squirrel.h