diff --git a/Documentation/debugger.rst b/Documentation/debugger.rst
index 5d758fc8736043ffdaea463daff8d127f4a6b7e6..94be7c20385a2d33b943395198cc0489b5db8a50 100644
--- a/Documentation/debugger.rst
+++ b/Documentation/debugger.rst
@@ -23,7 +23,7 @@ the following commands:
    $ ./bootstrap
    $ ./configure --disable-werror
 
-.. warning:
+.. warning::
     Make sure ``CMSIS-DAP Compliant Debugger`` is set to **yes (auto)** after
     running ``./configure`` (if it is not, you might need to install ``libhidapi-dev``
     (Ubuntu)). If you get errors making the documentation you can