diff --git a/sys/fido2/ctap/Kconfig b/sys/fido2/ctap/Kconfig
index 3c7bd8035808a..ce5c673bff6bf 100644
--- a/sys/fido2/ctap/Kconfig
+++ b/sys/fido2/ctap/Kconfig
@@ -87,6 +87,9 @@ endchoice
 config FIDO2_CTAP_FLASH_START_PAGE
     int "First flash page to store data in"
     default -1
+    help
+        Configuring this incorrectly can lead to firmware corruption so make sure
+        the flash page is located after the firmware.
 
 rsource "transport/Kconfig"
 
diff --git a/sys/fido2/doc.txt b/sys/fido2/doc.txt
index 6e4b35c38e4cb..74e1bf0b8f2b7 100644
--- a/sys/fido2/doc.txt
+++ b/sys/fido2/doc.txt
@@ -9,6 +9,8 @@
 /**
  * @defgroup    fido2 FIDO2 - Fast Identity Online 2
  * @ingroup     sys
+ * @brief       Description of the FIDO2 CTAP implementation in RIOT
+ * @author      Nils Ollrogge <nils.ollrogge@fu-berlin.de>
  *
  * @warning This feature is experimental!
  *          This API is experimental and in an early state - expect changes.
diff --git a/sys/include/fido2/ctap/ctap_mem.h b/sys/include/fido2/ctap/ctap_mem.h
index 15dffbe6d7949..f9b2bf4828ca8 100644
--- a/sys/include/fido2/ctap/ctap_mem.h
+++ b/sys/include/fido2/ctap/ctap_mem.h
@@ -42,6 +42,10 @@ extern "C" {
 
 /**
  * @brief First flash page to store data in
+ *
+ * @note This can corrupt firmware if CTAP_FLASH_START_PAGE is set to a
+ * flash page containing firmware. Therefore make sure that CTAP_FLASH_START_PAGE
+ * is located after the firmware.
  */
 #if defined(CONFIG_FIDO2_CTAP_FLASH_START_PAGE) && \
     (CONFIG_FIDO2_CTAP_FLASH_START_PAGE >= 0)
diff --git a/tests/sys_fido2_ctap/README.md b/tests/sys_fido2_ctap/README.md
index 7e6a336857f21..acd46d4008f41 100644
--- a/tests/sys_fido2_ctap/README.md
+++ b/tests/sys_fido2_ctap/README.md
@@ -31,6 +31,13 @@ Unit testing is based on the `fido2_tests` package.
 There are two test targets (fido2-test, fido2-test-up). The former requires no user
 interaction the latter does.
 
+Note:
+* The tests require python 3.6+.
+* The tests require [swig](http://www.swig.org/) to be installed on your host computer.
+* Running the tests for the first time will setup a virtual python environment (venv) and install python dependencies of the tests. To check the dependencies please refer to the `requirements.txt` of the [fido2-tests repository](https://github.com/solokeys/fido2-tests).
+* The unit tests will require you to reboot the authenticator multiple times. Be patient before continuing as it takes a few seconds for the connection between OS and authenticator to be re-established.
+* If you keep getting errors while trying to run the tests try changing to another git branch and back e.g. `git checkout branch1 && git checkout -` in order to remove build artifacts. Then re-flash the device with `make flash term` and try to run the tests again with `make fido2-test` or `make fido2-test-up`.
+
 fido2-test
 
 1. To make benchmarking faster disable user presence tests by enabling the CFLAG
@@ -43,9 +50,4 @@ fido2-test-up
 1. Make sure that the CFLAG `CONFIG_FIDO2_CTAP_DISABLE_UP` is disabled as this test target
   requires user interaction.
 2. Flash the device with `make flash`.
-3. Run the unit tests by running `make fido2-test-up` and follow the instructions about when to show user presence (by pressing button 1).
-
-Note:
-* The tests require python 3.6+.
-* Running the tests for the first time will setup a virtual python environment (venv) and install python dependencies of the tests. To check the dependencies please refer to the `requirements.txt` of the [fido2-tests repository](https://github.com/solokeys/fido2-tests).
-* The unit tests will require you to reboot the authenticator multiple times. Be patient before continuing as it takes a few seconds for the connection between OS and authenticator to be re-established.
+3. Run the unit tests by running `make fido2-test-up` and follow the instructions. E.g. when `.ACTIVATE UP ONCE` is displayed, press the configured UP button (default button 1) once.