diff --git a/phpBB/adm/style/admin.css b/phpBB/adm/style/admin.css
index 19a277e18d..b7c521a385 100644
--- a/phpBB/adm/style/admin.css
+++ b/phpBB/adm/style/admin.css
@@ -1721,6 +1721,11 @@ fieldset.submit-buttons legend {
 	height: 40px;
 }
 
+.mention-media-avatar img { /* TODO: reconsider for the future design */
+	max-width: 100%;
+	max-height: 100%;
+}
+
 svg { /* TODO: remove it after general normalization */
 	fill: currentColor;
 }
diff --git a/phpBB/styles/prosilver/theme/mentions.css b/phpBB/styles/prosilver/theme/mentions.css
index bb9ffff8d7..3400dde454 100644
--- a/phpBB/styles/prosilver/theme/mentions.css
+++ b/phpBB/styles/prosilver/theme/mentions.css
@@ -43,6 +43,11 @@
 	height: 40px;
 }
 
+.mention-media-avatar img { /* TODO: reconsider for the future design */
+	max-width: 100%;
+	max-height: 100%;
+}
+
 svg { /* TODO: remove it after general normalization */
 	fill: currentColor;
 }