diff --git a/README.md b/README.md
index 23de92b..c6dcced 100644
--- a/README.md
+++ b/README.md
@@ -130,6 +130,8 @@ See [Full Documentation](https://docs.rs/osakit/).
 
 Due to limitations on `OSAKit Framework`-side integer values returned from `JavaScript` code
 are limited to `i32` type.
+`OSAKit` calls must be made from the main thread, so, for example, the default `cargo test`s can fail,
+after stalling for 2 min, use a custom test harness like [libtest-mimic](https://github.com/LukasKalbertodt/libtest-mimic) with `--test-threads=1`.
 
 ## Supported platforms