diff --git a/platform/firefox/vapi-background.js b/platform/firefox/vapi-background.js
index 7aa440d2e..15d98726a 100644
--- a/platform/firefox/vapi-background.js
+++ b/platform/firefox/vapi-background.js
@@ -245,9 +245,11 @@ vAPI.browserSettings = {
                 if ( settingVal ) {
                     this.clear('network', 'prefetch-next');
                     this.clear('network.http', 'speculative-parallel-limit');
+                    this.clear('network.dns', 'disablePrefetch');
                 } else {
                     this.setValue('network', 'prefetch-next', false);
                     this.setValue('network.http', 'speculative-parallel-limit', 0);
+                    this.setValue('network.dns', 'disablePrefetch', true);
                 }
                 break;