diff --git a/dom/base/nsDocument.cpp b/dom/base/nsDocument.cpp
index c13e775a94..3edcb39020 100644
--- a/dom/base/nsDocument.cpp
+++ b/dom/base/nsDocument.cpp
@@ -2802,20 +2802,9 @@ nsDocument::GetPrincipal()
   return NodePrincipal();
 }
 
-extern bool sDisablePrefetchHTTPSPref;
-
 void
 nsDocument::SetPrincipal(nsIPrincipal *aNewPrincipal)
 {
-  if (aNewPrincipal && mAllowDNSPrefetch && sDisablePrefetchHTTPSPref) {
-    nsCOMPtr<nsIURI> uri;
-    aNewPrincipal->GetURI(getter_AddRefs(uri));
-    bool isHTTPS;
-    if (!uri || NS_FAILED(uri->SchemeIs("https", &isHTTPS)) ||
-        isHTTPS) {
-      mAllowDNSPrefetch = false;
-    }
-  }
   mNodeInfoManager->SetDocumentPrincipal(aNewPrincipal);
 
 #ifdef DEBUG
diff --git a/dom/html/nsHTMLDNSPrefetch.cpp b/dom/html/nsHTMLDNSPrefetch.cpp
index 6a7217021f..1b91d8041d 100644
--- a/dom/html/nsHTMLDNSPrefetch.cpp
+++ b/dom/html/nsHTMLDNSPrefetch.cpp
@@ -37,7 +37,6 @@ using namespace mozilla::dom;
 using namespace mozilla::net;
 
 static NS_DEFINE_CID(kDNSServiceCID, NS_DNSSERVICE_CID);
-bool sDisablePrefetchHTTPSPref;
 static bool sInitialized = false;
 static nsIDNSService *sDNSService = nullptr;
 static nsHTMLDNSPrefetch::nsDeferrals *sPrefetches = nullptr;
@@ -59,13 +58,6 @@ nsHTMLDNSPrefetch::Initialize()
 
   sPrefetches->Activate();
 
-  Preferences::AddBoolVarCache(&sDisablePrefetchHTTPSPref,
-                               "network.dns.disablePrefetchFromHTTPS");
-  
-  // Default is false, so we need an explicit call to prime the cache.
-  sDisablePrefetchHTTPSPref = 
-    Preferences::GetBool("network.dns.disablePrefetchFromHTTPS", true);
-  
   NS_IF_RELEASE(sDNSService);
   nsresult rv;
   rv = CallGetService(kDNSServiceCID, &sDNSService);