diff --git a/README.md b/README.md
index d2159855f8..d804371028 100644
--- a/README.md
+++ b/README.md
@@ -78,6 +78,8 @@ make
 ```
 
 Test outputs can be found in the build directory under `libuavcan`.
+Note that unit tests must be executed in real time, otherwise they may produce false warnings;
+this implies that they will likely fail if ran on a virtual machine or on a highly loaded system.
 
 Contributors, please follow the [Zubax Style Guide](https://github.com/Zubax/zubax_style_guide).