--- a/editor/libeditor/HTMLEditRules.cpp
+++ b/editor/libeditor/HTMLEditRules.cpp
@@ -6313,16 +6313,26 @@ HTMLEditRules::IsInListItem(nsINode* aNo
     if (HTMLEditUtils::IsListItem(parent)) {
       return parent;
     }
     parent = parent->GetParentElement();
   }
   return nullptr;
 }
 
+nsIAtom&
+HTMLEditRules::DefaultParagraphSeparator()
+{
+  MOZ_ASSERT(mHTMLEditor);
+  if (!mHTMLEditor) {
+    return *nsGkAtoms::div;
+  }
+  return ParagraphSeparatorElement(mHTMLEditor->GetDefaultParagraphSeparator());
+}
+
 /**
  * ReturnInHeader: do the right thing for returns pressed in headers
  */
 nsresult
 HTMLEditRules::ReturnInHeader(Selection& aSelection,
                               Element& aHeader,
                               nsINode& aNode,
                               int32_t aOffset)
@@ -6368,18 +6378,22 @@ HTMLEditRules::ReturnInHeader(Selection&
     // break after the header.
     nsCOMPtr<nsIContent> sibling =
       htmlEditor->GetNextHTMLSibling(headerParent, offset + 1);
     if (!sibling || !sibling->IsHTMLElement(nsGkAtoms::br)) {
       ClearCachedStyles();
       htmlEditor->mTypeInState->ClearAllProps();
 
       // Create a paragraph
+      nsIAtom& paraAtom = DefaultParagraphSeparator();
+      // We want a wrapper element even if we separate with <br>
       nsCOMPtr<Element> pNode =
-        htmlEditor->CreateNode(nsGkAtoms::p, headerParent, offset + 1);
+        htmlEditor->CreateNode(&paraAtom == nsGkAtoms::br ? nsGkAtoms::p
+                                                           : &paraAtom,
+                                headerParent, offset + 1);
       NS_ENSURE_STATE(pNode);
 
       // Append a <br> to it
       nsCOMPtr<Element> brNode = htmlEditor->CreateBR(pNode, 0);
       NS_ENSURE_STATE(brNode);
 
       // Set selection to before the break
       rv = aSelection.Collapse(pNode, 0);
@@ -6636,18 +6650,22 @@ HTMLEditRules::ReturnInListItem(Selectio
       rv = aSelection.Collapse(&aListItem, 0);
       NS_ENSURE_SUCCESS(rv, rv);
     } else {
       // Otherwise kill this item
       rv = htmlEditor->DeleteNode(&aListItem);
       NS_ENSURE_SUCCESS(rv, rv);
 
       // Time to insert a paragraph
+      nsIAtom& paraAtom = DefaultParagraphSeparator();
+      // We want a wrapper even if we separate with <br>
       nsCOMPtr<Element> pNode =
-        htmlEditor->CreateNode(nsGkAtoms::p, listParent, offset + 1);
+        htmlEditor->CreateNode(&paraAtom == nsGkAtoms::br ? nsGkAtoms::p
+                                                           : &paraAtom,
+                                listParent, offset + 1);
       NS_ENSURE_STATE(pNode);
 
       // Append a <br> to it
       nsCOMPtr<Element> brNode = htmlEditor->CreateBR(pNode, 0);
       NS_ENSURE_STATE(brNode);
 
       // Set selection to before the break
       rv = aSelection.Collapse(pNode, 0);

--- a/editor/libeditor/HTMLEditRules.h
+++ b/editor/libeditor/HTMLEditRules.h
@@ -268,16 +268,17 @@ protected:
   nsresult GetFormatString(nsIDOMNode* aNode, nsAString &outFormat);
   enum class Lists { no, yes };
   enum class Tables { no, yes };
   void GetInnerContent(nsINode& aNode,
                        nsTArray<OwningNonNull<nsINode>>& aOutArrayOfNodes,
                        int32_t* aIndex, Lists aLists = Lists::yes,
                        Tables aTables = Tables::yes);
   Element* IsInListItem(nsINode* aNode);
+  nsIAtom& DefaultParagraphSeparator();
   nsresult ReturnInHeader(Selection& aSelection, Element& aHeader,
                           nsINode& aNode, int32_t aOffset);
   nsresult ReturnInParagraph(Selection* aSelection, nsIDOMNode* aHeader,
                              nsIDOMNode* aTextNode, int32_t aOffset,
                              bool* aCancel, bool* aHandled);
   nsresult SplitParagraph(nsIDOMNode* aPara,
                           nsIContent* aBRNode,
                           Selection* aSelection,

--- a/testing/web-platform/meta/editing/run/insertparagraph.html.ini
+++ b/testing/web-platform/meta/editing/run/insertparagraph.html.ini
@@ -31,52 +31,31 @@
     expected: FAIL
 
   [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<table><tr><td>[foo\]</table>" compare innerHTML]
     expected: FAIL
 
   [[["defaultparagraphseparator","p"\],["insertparagraph",""\]\] "<table><tr><td>[foo\]</table>" compare innerHTML]
     expected: FAIL
 
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<ol><li>[foo\]<li>bar</ol>" compare innerHTML]
-    expected: FAIL
-
   [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<span>foo[\]</span>" compare innerHTML]
     expected: FAIL
 
   [[["defaultparagraphseparator","p"\],["insertparagraph",""\]\] "<span>foo[\]</span>" compare innerHTML]
     expected: FAIL
 
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<h1>foo[\]</h1>" compare innerHTML]
-    expected: FAIL
-
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<h1>foo[\]<br></h1>" compare innerHTML]
-    expected: FAIL
-
   [[["defaultparagraphseparator","p"\],["insertparagraph",""\]\] "<script>foo[\]bar</script>baz" compare innerHTML]
     expected: FAIL
 
   [[["stylewithcss","true"\],["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<div style=display:none>foo[\]bar</div>baz" compare innerHTML]
     expected: FAIL
 
   [[["stylewithcss","false"\],["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<div style=display:none>foo[\]bar</div>baz" compare innerHTML]
     expected: FAIL
 
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<ol><li>{}<br></li></ol>" compare innerHTML]
-    expected: FAIL
-
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<ol><li>foo<li>{}<br></ol>" compare innerHTML]
-    expected: FAIL
-
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<dl><dt>foo<dd>{}<br></dl>" compare innerHTML]
-    expected: FAIL
-
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<dl><dt>{}<br><dd>bar</dl>" compare innerHTML]
-    expected: FAIL
-
   [[["insertparagraph",""\]\] "<dl><dt>foo<dd>bar<dl><dt>{}<br><dd>baz</dl></dl>" compare innerHTML]
     expected: FAIL
 
   [[["insertparagraph",""\]\] "<dl><dt>foo<dd>bar<dl><dt>baz<dd>{}<br></dl></dl>" compare innerHTML]
     expected: FAIL
 
   [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<p>foo</p>{}<br>" compare innerHTML]
     expected: FAIL
@@ -103,19 +82,16 @@
     expected: FAIL
 
   [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<h1>foo</h1>{}<br><h2>bar</h2>" compare innerHTML]
     expected: FAIL
 
   [[["defaultparagraphseparator","p"\],["insertparagraph",""\]\] "<h1>foo</h1>{}<br><h2>bar</h2>" compare innerHTML]
     expected: FAIL
 
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<p>foo</p><h1>[bar\]</h1><p>baz</p>" compare innerHTML]
-    expected: FAIL
-
   [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<p>foo</p>{<h1>bar</h1>}<p>baz</p>" compare innerHTML]
     expected: FAIL
 
   [[["defaultparagraphseparator","p"\],["insertparagraph",""\]\] "<p>foo</p>{<h1>bar</h1>}<p>baz</p>" compare innerHTML]
     expected: FAIL
 
   [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<table><tr><td>foo[\]bar</table>" compare innerHTML]
     expected: FAIL
@@ -364,20 +340,8 @@
     expected: FAIL
 
   [[["stylewithcss","false"\],["defaultparagraphseparator","p"\],["insertparagraph",""\]\] "<div style=display:none>foo[\]bar</div>baz" compare innerHTML]
     expected: FAIL
 
   [[["insertparagraph",""\]\] "<listing>foo[\]bar</listing>" compare innerHTML]
     expected: FAIL
 
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "foo<ol><li>{}<br></li></ol>" compare innerHTML]
-    expected: FAIL
-
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<ol><li>{}<br></li></ol>foo" compare innerHTML]
-    expected: FAIL
-
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<ol><li>{}<br><li>bar</ol>" compare innerHTML]
-    expected: FAIL
-
-  [[["defaultparagraphseparator","div"\],["insertparagraph",""\]\] "<dl><dt>{}<br></dt></dl>" compare innerHTML]
-    expected: FAIL
-