diff --git a/gfx/thebes/gfxFcPlatformFontList.cpp b/gfx/thebes/gfxFcPlatformFontList.cpp
index baec762d707e..34db63699efb 100644
--- a/gfx/thebes/gfxFcPlatformFontList.cpp
+++ b/gfx/thebes/gfxFcPlatformFontList.cpp
@@ -1591,16 +1591,17 @@ void gfxFcPlatformFontList::InitSharedFontListForPlatform() {
       aFamilyName = ToCharPtr(canonical);
 
       // Add new family record if one doesn't already exist.
-      auto faceList = faces.LookupForAdd(keyName);
-      if (!faceList) {
-        faceList.OrInsert([]() { return new FaceInitArray; });
-        FontVisibility visibility =
-            aAppFont ? FontVisibility::Base : GetVisibilityForFamily(keyName);
-        families.AppendElement(fontlist::Family::InitData(
-            keyName, aFamilyName, fontlist::Family::kNoIndex, visibility,
-            /*bundled*/ aAppFont, /*badUnderline*/ false));
-      }
-      faceListPtr = faceList.Data().get();
+      faceListPtr = faces.WithEntryHandle(keyName, [&](auto&& faceList) {
+        if (!faceList) {
+          faceList.Insert(new FaceInitArray);
+          FontVisibility visibility =
+              aAppFont ? FontVisibility::Base : GetVisibilityForFamily(keyName);
+          families.AppendElement(fontlist::Family::InitData(
+              keyName, aFamilyName, fontlist::Family::kNoIndex, visibility,
+              /*bundled*/ aAppFont, /*badUnderline*/ false));
+        }
+        return faceList.Data().get();
+      });
     }
 
     char* s = (char*)FcNameUnparse(aPattern);
@@ -1649,17 +1650,18 @@ void gfxFcPlatformFontList::InitSharedFontListForPlatform() {
       keyName = otherFamilyName;
       ToLowerCase(keyName);
 
-      auto faceList = faces.LookupForAdd(keyName);
-      if (!faceList) {
-        faceList.OrInsert([]() { return new FaceInitArray; });
-        FontVisibility visibility =
-            aAppFont ? FontVisibility::Base : GetVisibilityForFamily(keyName);
-        families.AppendElement(fontlist::Family::InitData(
-            keyName, otherFamilyName, fontlist::Family::kNoIndex, visibility,
-            /*bundled*/ aAppFont, /*badUnderline*/ false));
-      }
-      faceList.Data()->AppendElement(fontlist::Face::InitData{
-          descriptor, 0, false, weight, stretch, style});
+      faces.WithEntryHandle(keyName, [&](auto&& faceList) {
+        if (!faceList) {
+          faceList.Insert(new FaceInitArray);
+          FontVisibility visibility =
+              aAppFont ? FontVisibility::Base : GetVisibilityForFamily(keyName);
+          families.AppendElement(fontlist::Family::InitData(
+              keyName, otherFamilyName, fontlist::Family::kNoIndex, visibility,
+              /*bundled*/ aAppFont, /*badUnderline*/ false));
+        }
+        faceList.Data()->AppendElement(fontlist::Face::InitData{
+            descriptor, 0, false, weight, stretch, style});
+      });
 
       n++;
       if (n == int(cIndex)) {
diff --git a/gfx/thebes/gfxPlatformFontList.cpp b/gfx/thebes/gfxPlatformFontList.cpp
index c8f9c3cc2f10..0385495eff95 100644
--- a/gfx/thebes/gfxPlatformFontList.cpp
+++ b/gfx/thebes/gfxPlatformFontList.cpp
@@ -1584,8 +1584,10 @@ gfxFontEntry* gfxPlatformFontList::FindFontForFamily(
 
 gfxFontEntry* gfxPlatformFontList::GetOrCreateFontEntry(
     fontlist::Face* aFace, const fontlist::Family* aFamily) {
-  return mFontEntries.LookupForAdd(aFace).OrInsert(
-      [=]() { return CreateFontEntry(aFace, aFamily); });
+  return mFontEntries.WithEntryHandle(aFace, [&](auto&& entry) {
+    return entry.OrInsertWith([=] { return CreateFontEntry(aFace, aFamily); })
+        .get();
+  });
 }
 
 void gfxPlatformFontList::AddOtherFamilyName(