diff --git a/dom/base/nsContentUtils.cpp b/dom/base/nsContentUtils.cpp
index 4a941aa70288..cce948c725df 100644
--- a/dom/base/nsContentUtils.cpp
+++ b/dom/base/nsContentUtils.cpp
@@ -2116,14 +2116,6 @@ nsContentUtils::IsCallerContentXBL()
     return xpc::IsContentXBLScope(c);
 }
 
-
-bool
-nsContentUtils::IsImageSrcSetDisabled()
-{
-  return Preferences::GetBool("dom.disable_image_src_set") &&
-         !IsCallerChrome();
-}
-
 // static
 bool
 nsContentUtils::LookupBindingMember(JSContext* aCx, nsIContent *aContent,
diff --git a/dom/base/nsContentUtils.h b/dom/base/nsContentUtils.h
index 426fa1d2c328..18b79bcb23b7 100644
--- a/dom/base/nsContentUtils.h
+++ b/dom/base/nsContentUtils.h
@@ -236,8 +236,6 @@ public:
     return SubjectPrincipal();
   }
 
-  static bool     IsImageSrcSetDisabled();
-
   static bool LookupBindingMember(JSContext* aCx, nsIContent *aContent,
                                   JS::Handle<jsid> aId,
                                   JS::MutableHandle<JSPropertyDescriptor> aDesc);
diff --git a/dom/html/HTMLImageElement.cpp b/dom/html/HTMLImageElement.cpp
index f3505766a67c..b339eab749cc 100644
--- a/dom/html/HTMLImageElement.cpp
+++ b/dom/html/HTMLImageElement.cpp
@@ -535,12 +535,6 @@ HTMLImageElement::SetAttr(int32_t aNameSpaceID, nsIAtom* aName,
   if (aNameSpaceID == kNameSpaceID_None &&
       aName == nsGkAtoms::src) {
 
-    // This is for dom.disable_image_src_set, which predates "srcset"
-    // as an attribute. See Bug 773429
-    if (nsContentUtils::IsImageSrcSetDisabled()) {
-      return NS_OK;
-    }
-
     if (InResponsiveMode()) {
       if (mResponsiveSelector &&
           mResponsiveSelector->Content() == this) {
diff --git a/dom/svg/SVGFEImageElement.cpp b/dom/svg/SVGFEImageElement.cpp
index dbd0a68b1455..e085f00895ed 100644
--- a/dom/svg/SVGFEImageElement.cpp
+++ b/dom/svg/SVGFEImageElement.cpp
@@ -114,11 +114,6 @@ SVGFEImageElement::AfterSetAttr(int32_t aNamespaceID, nsIAtom* aName,
     // If there is a frame then it should deal with loading as the image
     // url may be animated.
     if (!GetPrimaryFrame()) {
-
-      // Prevent setting image.src by exiting early
-      if (nsContentUtils::IsImageSrcSetDisabled()) {
-        return NS_OK;
-      }
       if (aValue) {
         LoadSVGImage(true, aNotify);
       } else {
diff --git a/dom/svg/SVGImageElement.cpp b/dom/svg/SVGImageElement.cpp
index a2224e326d80..144e375f2dc8 100644
--- a/dom/svg/SVGImageElement.cpp
+++ b/dom/svg/SVGImageElement.cpp
@@ -143,12 +143,6 @@ SVGImageElement::AfterSetAttr(int32_t aNamespaceID, nsIAtom* aName,
     // If there is a frame then it should deal with loading as the image
     // url may be animated
     if (!GetPrimaryFrame()) {
-
-      // Prevent setting image.src by exiting early
-      if (nsContentUtils::IsImageSrcSetDisabled()) {
-        return NS_OK;
-      }
-
       if (aValue) {
         LoadSVGImage(true, aNotify);
       } else {
diff --git a/dom/svg/SVGImageElement.h b/dom/svg/SVGImageElement.h
index 69ef9c7d2e10..7835b9b3538e 100644
--- a/dom/svg/SVGImageElement.h
+++ b/dom/svg/SVGImageElement.h
@@ -68,8 +68,6 @@ public:
 
   void MaybeLoadSVGImage();
 
-  bool IsImageSrcSetDisabled() const;
-
   // WebIDL
   already_AddRefed<SVGAnimatedLength> X();
   already_AddRefed<SVGAnimatedLength> Y();
diff --git a/layout/svg/SVGFEImageFrame.cpp b/layout/svg/SVGFEImageFrame.cpp
index 375042707fe0..9cdd1a6424ea 100644
--- a/layout/svg/SVGFEImageFrame.cpp
+++ b/layout/svg/SVGFEImageFrame.cpp
@@ -130,12 +130,6 @@ SVGFEImageFrame::AttributeChanged(int32_t  aNameSpaceID,
   }
   if (aNameSpaceID == kNameSpaceID_XLink &&
       aAttribute == nsGkAtoms::href) {
-
-    // Prevent setting image.src by exiting early
-    if (nsContentUtils::IsImageSrcSetDisabled()) {
-      return NS_OK;
-    }
-
     if (element->mStringAttributes[SVGFEImageElement::HREF].IsExplicitlySet()) {
       element->LoadSVGImage(true, true);
     } else {
diff --git a/layout/svg/nsSVGImageFrame.cpp b/layout/svg/nsSVGImageFrame.cpp
index 37dc53787ab1..b54e2ce8a4b8 100644
--- a/layout/svg/nsSVGImageFrame.cpp
+++ b/layout/svg/nsSVGImageFrame.cpp
@@ -208,11 +208,6 @@ nsSVGImageFrame::AttributeChanged(int32_t         aNameSpaceID,
   }
   if (aNameSpaceID == kNameSpaceID_XLink &&
       aAttribute == nsGkAtoms::href) {
-
-    // Prevent setting image.src by exiting early
-    if (nsContentUtils::IsImageSrcSetDisabled()) {
-      return NS_OK;
-    }
     SVGImageElement *element = static_cast<SVGImageElement*>(mContent);
 
     if (element->mStringAttributes[SVGImageElement::HREF].IsExplicitlySet()) {
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index 6b03f0558594..c3b286311065 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -1036,7 +1036,6 @@ pref("editor.positioning.offset",            0);
 
 // Scripts & Windows prefs
 pref("dom.disable_beforeunload",            false);
-pref("dom.disable_image_src_set",           false);
 pref("dom.disable_window_flip",             false);
 pref("dom.disable_window_move_resize",      false);
 pref("dom.disable_window_status_change",    false);