diff --git a/layout/mathml/nsMathMLContainerFrame.cpp b/layout/mathml/nsMathMLContainerFrame.cpp
index 342bee7fd869..a5d57862df01 100644
--- a/layout/mathml/nsMathMLContainerFrame.cpp
+++ b/layout/mathml/nsMathMLContainerFrame.cpp
@@ -1343,22 +1343,16 @@ nscoord nsMathMLContainerFrame::FixInterFrameSpacing(
 }
 
 /* static */
-void nsMathMLContainerFrame::DidReflowChildren(nsIFrame* aFirst,
-                                               nsIFrame* aStop)
-
-{
-  if (MOZ_UNLIKELY(!aFirst)) return;
-
-  for (nsIFrame* frame = aFirst; frame != aStop;
-       frame = frame->GetNextSibling()) {
-    NS_ASSERTION(frame, "aStop isn't a sibling");
-    if (frame->HasAnyStateBits(NS_FRAME_IN_REFLOW)) {
-      // finish off principal descendants, too
-      nsIFrame* grandchild = frame->PrincipalChildList().FirstChild();
-      if (grandchild) DidReflowChildren(grandchild, nullptr);
-
-      frame->DidReflow(frame->PresContext(), nullptr);
+void nsMathMLContainerFrame::DidReflowChildren(nsIFrame* aFirst) {
+  for (nsIFrame* frame = aFirst; frame; frame = frame->GetNextSibling()) {
+    if (!frame->HasAnyStateBits(NS_FRAME_IN_REFLOW)) {
+      continue;
     }
+    if (nsIFrame* grandchild = frame->PrincipalChildList().FirstChild()) {
+      // Finish off principal descendants, too
+      DidReflowChildren(grandchild);
+    }
+    frame->DidReflow(frame->PresContext(), nullptr);
   }
 }
 
diff --git a/layout/mathml/nsMathMLContainerFrame.h b/layout/mathml/nsMathMLContainerFrame.h
index ec3d28e816c1..a462e921b010 100644
--- a/layout/mathml/nsMathMLContainerFrame.h
+++ b/layout/mathml/nsMathMLContainerFrame.h
@@ -361,12 +361,10 @@ class nsMathMLContainerFrame : public nsContainerFrame, public nsMathMLFrame {
   void GatherAndStoreOverflow(ReflowOutput* aMetrics);
 
   /**
-   * Call DidReflow() if the NS_FRAME_IN_REFLOW frame bit is set on aFirst and
-   * all its next siblings up to, but not including, aStop.
-   * aStop == nullptr meaning all next siblings with the bit set.
-   * The method does nothing if aFirst == nullptr.
+   * Call DidReflow() if the NS_FRAME_IN_REFLOW frame bit is set on aFirst
+   * and all its next siblings. The method does nothing if aFirst == nullptr.
    */
-  static void DidReflowChildren(nsIFrame* aFirst, nsIFrame* aStop = nullptr);
+  static void DidReflowChildren(nsIFrame* aFirst);
 
   /**
    * Recompute mIntrinsicISize if it's not already up to date.