diff --git a/Readme.md b/Readme.md
index 859bb1568f4..9cdd59f94f8 100644
--- a/Readme.md
+++ b/Readme.md
@@ -70,11 +70,17 @@ $ ../gcc/configure \
 $ make -j4 # You can replace `4` with another number depending on how many cores you have.
 ```
 
-If you want to run libgccjit tests, you will need to also enable the C++ language in the `configure`:
+If you want to run libgccjit tests, you will need to
+* Enable the C++ language in the `configure` step:
 
 ```bash
 --enable-languages=jit,c++
 ```
+* Install [dejagnu](https://www.gnu.org/software/dejagnu/#downloading) to run the tests:
+
+```bash
+$ sudo apt install dejagnu
+```
 
 Then to run libgccjit tests: