diff --git a/src/public/app/services/library_loader.js b/src/public/app/services/library_loader.js
index a6b770038..f5299ae33 100644
--- a/src/public/app/services/library_loader.js
+++ b/src/public/app/services/library_loader.js
@@ -158,7 +158,16 @@ async function requireCss(url, prependAssetPath = true) {
 
 let highlightingThemeEl = null;
 function loadHighlightingTheme(theme) {
-    if (!theme) {
+    if (!theme) {        
+        return;
+    }
+
+    if (theme === "none") {
+        // Deactivate the theme.
+        if (highlightingThemeEl) {
+            highlightingThemeEl.remove();
+            highlightingThemeEl = null;
+        }
         return;
     }