diff --git a/CHANGES.md b/CHANGES.md
index 786248e803d80634147a103c614a60c71867aa15..6c06ef693f5984f19a9febf709d312a828f5988d 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -6,6 +6,7 @@ Changes
 
 ### Unreleased
 
+* 2021-02-05 - Bugfix: Moodle core Back-to-top button was not clickable over Boost Campus footer
 * 2021-02-05 - Move Moodle Plugin CI from Travis CI to Github actions
 
 ### Release v3.9-r5
diff --git a/scss/post.scss b/scss/post.scss
index 68d75c0f4d0e0f549782207fe77b22c0678e588d..6b852d7456f670ad1ee5c1aa1c20567be8d23482 100644
--- a/scss/post.scss
+++ b/scss/post.scss
@@ -930,7 +930,14 @@ a[href^="mailto"]::before {
   Additional Elements
   -------------------------------------*/
 
-/* Back to top button */
+/* Moodle Core Back to top button */
+body.scrolled #goto-top-link {
+    /* For unknown reasons, the Moodle Core Back to top button is made unclickable by the Boost Campus footer.
+       We fix this by simply raising the z-index of the button. */
+    z-index: $zindex-tooltip;
+}
+
+/* Boost Campus Back to top button */
 #back-to-top {
     display: none;
     position: fixed;