diff --git a/layout/generic/nsCanvasFrame.cpp b/layout/generic/nsCanvasFrame.cpp
index c8275c24cc32..a676c3253fce 100644
--- a/layout/generic/nsCanvasFrame.cpp
+++ b/layout/generic/nsCanvasFrame.cpp
@@ -375,7 +375,7 @@ nsDisplayCanvasBackgroundImage::IsSingleFixedPositionImage(nsDisplayListBuilder*
   nsRect borderArea = nsRect(ToReferenceFrame(), mFrame->GetSize());
   const nsStyleImageLayers::Layer &layer = mBackgroundStyle->StyleBackground()->mImage.mLayers[mLayer];
 
-  if (layer.mAttachment != NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED)
+  if (layer.mAttachment != StyleImageLayerAttachment::Fixed)
     return false;
 
    nsBackgroundLayerState state =
diff --git a/layout/painting/nsCSSRendering.cpp b/layout/painting/nsCSSRendering.cpp
index 048ab2c5d740..8ed0d73a2a02 100644
--- a/layout/painting/nsCSSRendering.cpp
+++ b/layout/painting/nsCSSRendering.cpp
@@ -2334,7 +2334,7 @@ nsCSSRendering::GetImageLayerClip(const nsStyleImageLayers::Layer& aLayer,
   aClipState->mBGClipArea = clipBorderArea;
 
   if (aForFrame->IsScrollFrame() &&
-      NS_STYLE_IMAGELAYER_ATTACHMENT_LOCAL == aLayer.mAttachment) {
+      StyleImageLayerAttachment::Local == aLayer.mAttachment) {
     // As of this writing, this is still in discussion in the CSS Working Group
     // http://lists.w3.org/Archives/Public/www-style/2013Jul/0250.html
 
@@ -2947,7 +2947,7 @@ nsCSSRendering::ComputeImageLayerPositioningArea(nsPresContext* aPresContext,
   LayoutFrameType frameType = aForFrame->Type();
   nsIFrame* geometryFrame = aForFrame;
   if (MOZ_UNLIKELY(frameType == LayoutFrameType::Scroll &&
-                   NS_STYLE_IMAGELAYER_ATTACHMENT_LOCAL == aLayer.mAttachment)) {
+                   StyleImageLayerAttachment::Local == aLayer.mAttachment)) {
     nsIScrollableFrame* scrollableFrame = do_QueryFrame(aForFrame);
     positionArea = nsRect(
       scrollableFrame->GetScrolledFrame()->GetPosition()
@@ -3008,7 +3008,7 @@ nsCSSRendering::ComputeImageLayerPositioningArea(nsPresContext* aPresContext,
   }
 
   nsIFrame* attachedToFrame = aForFrame;
-  if (NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED == aLayer.mAttachment) {
+  if (StyleImageLayerAttachment::Fixed == aLayer.mAttachment) {
     // If it's a fixed background attachment, then the image is placed
     // relative to the viewport, which is the area of the root frame
     // in a screen context or the page content frame in a print context.
@@ -3283,7 +3283,7 @@ nsCSSRendering::PrepareImageLayer(nsPresContext* aPresContext,
   // where the background can be drawn to the viewport.
   nsRect bgClipRect = aBGClipRect;
 
-  if (NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED == aLayer.mAttachment &&
+  if (StyleImageLayerAttachment::Fixed == aLayer.mAttachment &&
       !transformedFixed &&
       (aFlags & nsCSSRendering::PAINTBG_TO_WINDOW)) {
     bgClipRect = positionArea + aBorderArea.TopLeft();
diff --git a/layout/painting/nsDisplayList.cpp b/layout/painting/nsDisplayList.cpp
index e7636ac13ec6..f0b83af97157 100644
--- a/layout/painting/nsDisplayList.cpp
+++ b/layout/painting/nsDisplayList.cpp
@@ -3501,7 +3501,7 @@ nsDisplayBackgroundImage::GetInitData(nsDisplayListBuilder* aBuilder,
   // if it's affected by a transform.
   // See https://www.w3.org/Bugs/Public/show_bug.cgi?id=17521.
   bool shouldTreatAsFixed =
-    layer.mAttachment == NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED && !isTransformedFixed;
+    layer.mAttachment == StyleImageLayerAttachment::Fixed && !isTransformedFixed;
 
   bool shouldFixToViewport = shouldTreatAsFixed && !layer.mImage.IsEmpty();
   bool isRasterImage = state.mImageRenderer.IsRasterImage();
diff --git a/layout/style/ServoBindings.toml b/layout/style/ServoBindings.toml
index 1c2a4dd1326f..9185b78359db 100644
--- a/layout/style/ServoBindings.toml
+++ b/layout/style/ServoBindings.toml
@@ -173,6 +173,7 @@ rusty-enums = [
     "mozilla::StyleUserFocus",
     "mozilla::StyleUserSelect",
     "mozilla::StyleImageLayerRepeat",
+    "mozilla::StyleImageLayerAttachment",
     "mozilla::StyleBoxDecorationBreak",
     "mozilla::StyleRuleInclusion",
     "mozilla::StyleGridTrackBreadth",
@@ -243,6 +244,7 @@ whitelist-types = [
     "mozilla::LookAndFeel",
     "mozilla::gfx::Float",
     "mozilla::gfx::FontVariation",
+    "mozilla::StyleImageLayerAttachment",
     ".*ThreadSafe.*Holder",
     "AnonymousContent",
     "AudioContext",
diff --git a/layout/style/nsCSSProps.cpp b/layout/style/nsCSSProps.cpp
index dc3cb650ab4e..f39e0cf6b9e4 100644
--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -447,9 +447,9 @@ const KTableEntry nsCSSProps::kTransformStyleKTable[] = {
 };
 
 const KTableEntry nsCSSProps::kImageLayerAttachmentKTable[] = {
-  { eCSSKeyword_fixed, NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED },
-  { eCSSKeyword_scroll, NS_STYLE_IMAGELAYER_ATTACHMENT_SCROLL },
-  { eCSSKeyword_local, NS_STYLE_IMAGELAYER_ATTACHMENT_LOCAL },
+  { eCSSKeyword_fixed, StyleImageLayerAttachment::Fixed },
+  { eCSSKeyword_scroll, StyleImageLayerAttachment::Scroll },
+  { eCSSKeyword_local, StyleImageLayerAttachment::Local },
   { eCSSKeyword_UNKNOWN, -1 }
 };
 
diff --git a/layout/style/nsStyleConsts.h b/layout/style/nsStyleConsts.h
index 83f338530a24..61d16ea2dc8d 100644
--- a/layout/style/nsStyleConsts.h
+++ b/layout/style/nsStyleConsts.h
@@ -254,9 +254,11 @@ enum class FillMode : uint8_t;
 #define NS_STYLE_ANIMATION_PLAY_STATE_PAUSED      1
 
 // See nsStyleImageLayers
-#define NS_STYLE_IMAGELAYER_ATTACHMENT_SCROLL        0
-#define NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED         1
-#define NS_STYLE_IMAGELAYER_ATTACHMENT_LOCAL         2
+enum class StyleImageLayerAttachment : uint8_t {
+    Scroll,
+    Fixed,
+    Local
+};
 
 // A magic value that we use for our "pretend that background-clip is
 // 'padding' when we have a solid border" optimization.  This isn't
diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
index 1f4ab553b169..0e87b27cdb88 100644
--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -3111,7 +3111,7 @@ nsStyleImageLayers::Size::operator==(const Size& aOther) const
 
 nsStyleImageLayers::Layer::Layer()
   : mClip(StyleGeometryBox::BorderBox)
-  , mAttachment(NS_STYLE_IMAGELAYER_ATTACHMENT_SCROLL)
+  , mAttachment(StyleImageLayerAttachment::Scroll)
   , mBlendMode(NS_STYLE_BLEND_NORMAL)
   , mComposite(NS_STYLE_MASK_COMPOSITE_ADD)
   , mMaskMode(NS_STYLE_MASK_MODE_MATCH_SOURCE)
@@ -3350,7 +3350,7 @@ nsStyleBackground::HasFixedBackground(nsIFrame* aFrame) const
 {
   NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, mImage) {
     const nsStyleImageLayers::Layer &layer = mImage.mLayers[i];
-    if (layer.mAttachment == NS_STYLE_IMAGELAYER_ATTACHMENT_FIXED &&
+    if (layer.mAttachment == StyleImageLayerAttachment::Fixed &&
         !layer.mImage.IsEmpty() &&
         !nsLayoutUtils::IsTransformed(aFrame)) {
       return true;
diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index ca6475a77aed..ce8b08aa3d16 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -653,6 +653,7 @@ struct nsStyleImageLayers {
 
   struct Layer {
     typedef mozilla::StyleGeometryBox StyleGeometryBox;
+    typedef mozilla::StyleImageLayerAttachment StyleImageLayerAttachment;
 
     nsStyleImage  mImage;         // [reset]
     mozilla::Position mPosition;  // [reset]
@@ -660,12 +661,13 @@ struct nsStyleImageLayers {
     StyleGeometryBox  mClip;      // [reset] See nsStyleConsts.h
     MOZ_INIT_OUTSIDE_CTOR
       StyleGeometryBox mOrigin;   // [reset] See nsStyleConsts.h
-    uint8_t       mAttachment;    // [reset] See nsStyleConsts.h
+    StyleImageLayerAttachment mAttachment;
+                                  // [reset] See nsStyleConsts.h
                                   // background-only property
                                   // This property is used for background layer
                                   // only. For a mask layer, it should always
                                   // be the initial value, which is
-                                  // NS_STYLE_IMAGELAYER_ATTACHMENT_SCROLL.
+                                  // StyleImageLayerAttachment::Scroll.
     uint8_t       mBlendMode;     // [reset] See nsStyleConsts.h
                                   // background-only property
                                   // This property is used for background layer
diff --git a/layout/style/nsStyleStructInlines.h b/layout/style/nsStyleStructInlines.h
index 5e0fd1accf04..48fd263e6c15 100644
--- a/layout/style/nsStyleStructInlines.h
+++ b/layout/style/nsStyleStructInlines.h
@@ -266,7 +266,7 @@ nsStyleBackground::HasLocalBackground() const
   NS_FOR_VISIBLE_IMAGE_LAYERS_BACK_TO_FRONT(i, mImage) {
     const nsStyleImageLayers::Layer& layer = mImage.mLayers[i];
     if (!layer.mImage.IsEmpty() &&
-        layer.mAttachment == NS_STYLE_IMAGELAYER_ATTACHMENT_LOCAL) {
+        layer.mAttachment == mozilla::StyleImageLayerAttachment::Local) {
       return true;
     }
   }
diff --git a/servo/components/style/properties/longhand/background.mako.rs b/servo/components/style/properties/longhand/background.mako.rs
index d6b9e6e69ba8..a1f1b0394340 100644
--- a/servo/components/style/properties/longhand/background.mako.rs
+++ b/servo/components/style/properties/longhand/background.mako.rs
@@ -54,7 +54,7 @@ ${helpers.predefined_type(
 ${helpers.single_keyword("background-attachment",
                          "scroll fixed" + (" local" if product == "gecko" else ""),
                          vector=True,
-                         gecko_constant_prefix="NS_STYLE_IMAGELAYER_ATTACHMENT",
+                         gecko_enum_prefix="StyleImageLayerAttachment",
                          spec="https://drafts.csswg.org/css-backgrounds/#the-background-attachment",
                          animation_value_type="discrete",
                          flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER")}