diff --git a/test/fixtures/execute/README.md b/test/fixtures/execute/README.md
index 25dc15a8..83b06e79 100644
--- a/test/fixtures/execute/README.md
+++ b/test/fixtures/execute/README.md
@@ -1 +1,3 @@
 Tests in this folder are run in scratch by integration/execute.js. The tests can SAY test messages that map to tap methods. Read integration/execute.js for more.
+
+Note: Tests whose names start with `tw-` are added by TurboWarp. Because these tests are often based on real Scratch projects, they are licensed under the [Creative Commons Attribution-ShareAlike 2.0 license](https://creativecommons.org/licenses/by-sa/2.0/). They often contain the ID of the project they're based on in their file name, or otherwise in a comment inside the project.