diff --git a/dom/base/Selection.cpp b/dom/base/Selection.cpp
index 383e9f2ff6b8..f173388d4209 100644
--- a/dom/base/Selection.cpp
+++ b/dom/base/Selection.cpp
@@ -519,11 +519,12 @@ nsresult Selection::MaybeAddTableCellRange(nsRange& aRange, bool* aDidAddRange,
   return AddRangesForSelectableNodes(&aRange, aOutIndex);
 }
 
-Selection::Selection(nsFrameSelection* aFrameSelection)
+Selection::Selection(SelectionType aSelectionType,
+                     nsFrameSelection* aFrameSelection)
     : mFrameSelection(aFrameSelection),
       mCachedOffsetForFrame(nullptr),
       mDirection(eDirNext),
-      mSelectionType(SelectionType::eNormal),
+      mSelectionType(aSelectionType),
       mCustomColors(nullptr),
       mSelectionChangeBlockerCount(0),
       mUserInitiated(false),
diff --git a/dom/base/Selection.h b/dom/base/Selection.h
index b334e8bf068e..1c3a9d03905a 100644
--- a/dom/base/Selection.h
+++ b/dom/base/Selection.h
@@ -63,7 +63,8 @@ class Selection final : public nsSupportsWeakReference,
   /**
    * @param aFrameSelection can be nullptr.
    */
-  explicit Selection(nsFrameSelection* aFrameSelection);
+  explicit Selection(SelectionType aSelectionType,
+                     nsFrameSelection* aFrameSelection);
 
   MOZ_DECLARE_WEAKREFERENCE_TYPENAME(Selection)
 
@@ -645,9 +646,6 @@ class Selection final : public nsSupportsWeakReference,
 
  public:
   SelectionType GetType() const { return mSelectionType; }
-  void SetType(SelectionType aSelectionType) {
-    mSelectionType = aSelectionType;
-  }
 
   SelectionCustomColors* GetCustomColors() const { return mCustomColors.get(); }
 
@@ -834,7 +832,7 @@ class Selection final : public nsSupportsWeakReference,
   nsRevocableEventPtr<ScrollSelectionIntoViewEvent> mScrollEvent;
   CachedOffsetForFrame* mCachedOffsetForFrame;
   nsDirection mDirection;
-  SelectionType mSelectionType;
+  const SelectionType mSelectionType;
   UniquePtr<SelectionCustomColors> mCustomColors;
 
   // Non-zero if we don't want any changes we make to the selection to be
diff --git a/dom/base/nsCopySupport.cpp b/dom/base/nsCopySupport.cpp
index 73f62884738e..b6f57eff3d72 100644
--- a/dom/base/nsCopySupport.cpp
+++ b/dom/base/nsCopySupport.cpp
@@ -406,7 +406,7 @@ nsresult nsCopySupport::GetTransferableForNode(
   // Make a temporary selection with aNode in a single range.
   // XXX We should try to get rid of the Selection object here.
   // XXX bug 1245883
-  RefPtr<Selection> selection = new Selection(nullptr);
+  RefPtr<Selection> selection = new Selection(SelectionType::eNormal, nullptr);
   RefPtr<nsRange> range = nsRange::Create(aNode);
   ErrorResult result;
   range->SelectNode(*aNode, result);
diff --git a/dom/base/nsDocumentEncoder.cpp b/dom/base/nsDocumentEncoder.cpp
index 85eb83d60346..028828286114 100644
--- a/dom/base/nsDocumentEncoder.cpp
+++ b/dom/base/nsDocumentEncoder.cpp
@@ -1378,7 +1378,7 @@ nsHTMLCopyEncoder::SetSelection(Selection* aSelection) {
   // there's no Clone() for selection! fix...
   // nsresult rv = aSelection->Clone(getter_AddRefs(mSelection);
   // NS_ENSURE_SUCCESS(rv, rv);
-  mEncodingScope.mSelection = new Selection(nullptr);
+  mEncodingScope.mSelection = new Selection(SelectionType::eNormal, nullptr);
 
   // loop thru the ranges in the selection
   for (uint32_t rangeIdx = 0; rangeIdx < rangeCount; ++rangeIdx) {
diff --git a/layout/generic/nsFrameSelection.cpp b/layout/generic/nsFrameSelection.cpp
index 41498c50e3f8..850751de30f7 100644
--- a/layout/generic/nsFrameSelection.cpp
+++ b/layout/generic/nsFrameSelection.cpp
@@ -304,8 +304,7 @@ struct MOZ_RAII AutoPrepareFocusRange {
 nsFrameSelection::nsFrameSelection(PresShell* aPresShell, nsIContent* aLimiter,
                                    const bool aAccessibleCaretEnabled) {
   for (size_t i = 0; i < ArrayLength(mDomSelections); i++) {
-    mDomSelections[i] = new Selection(this);
-    mDomSelections[i]->SetType(kPresentSelectionTypes[i]);
+    mDomSelections[i] = new Selection(kPresentSelectionTypes[i], this);
   }
 
 #ifdef XP_MACOSX