diff --git a/theme/boost/scss/moodle/icons.scss b/theme/boost/scss/moodle/icons.scss
index 7947814e6e7..4f9ed0de6ba 100644
--- a/theme/boost/scss/moodle/icons.scss
+++ b/theme/boost/scss/moodle/icons.scss
@@ -144,6 +144,7 @@ $iconsizes: map-merge((
     .activityicon,
     .icon {
         margin: 0;
+        font-size: $icon-medium-width;
         height: $icon-medium-width;
         width: $icon-medium-height;
     }
diff --git a/theme/boost/style/moodle.css b/theme/boost/style/moodle.css
index d8eaad610c5..ea7a7b6347b 100644
--- a/theme/boost/style/moodle.css
+++ b/theme/boost/style/moodle.css
@@ -26143,6 +26143,7 @@ blockquote {
 .activityiconcontainer .activityicon,
 .activityiconcontainer .icon {
   margin: 0;
+  font-size: 24px;
   height: 24px;
   width: 24px;
 }
diff --git a/theme/classic/style/moodle.css b/theme/classic/style/moodle.css
index 30666dc171d..64ddef6420d 100644
--- a/theme/classic/style/moodle.css
+++ b/theme/classic/style/moodle.css
@@ -26143,6 +26143,7 @@ blockquote {
 .activityiconcontainer .activityicon,
 .activityiconcontainer .icon {
   margin: 0;
+  font-size: 24px;
   height: 24px;
   width: 24px;
 }