diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 967f57b65..93089495b 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -42,4 +42,16 @@ pip3.6 install flake8 coveralls
 flake8 freqtrade
 ```
 
+## 3. Test if all type-hints are correct
 
+**Install packages** (If not already installed)
+
+``` bash
+pip3.6 install mypy
+```
+
+**Run mypy**
+
+``` bash
+mypy freqtrade
+```