diff --git a/layout/generic/nsBlockFrame.cpp b/layout/generic/nsBlockFrame.cpp
index 2ef01d960c10..aeef48d90bfd 100644
--- a/layout/generic/nsBlockFrame.cpp
+++ b/layout/generic/nsBlockFrame.cpp
@@ -490,7 +490,7 @@ void nsBlockFrame::List(FILE* out, const char* aPrefix,
   nsCString str;
   ListGeneric(str, aPrefix, aFlags);
 
-  fprintf_stderr(out, "%s<\n", str.get());
+  fprintf_stderr(out, "%s <\n", str.get());
 
   nsCString pfx(aPrefix);
   pfx += "  ";
diff --git a/layout/generic/nsContainerFrame.cpp b/layout/generic/nsContainerFrame.cpp
index cef84fa88080..fdd2da34f6f3 100644
--- a/layout/generic/nsContainerFrame.cpp
+++ b/layout/generic/nsContainerFrame.cpp
@@ -3306,8 +3306,13 @@ void nsContainerFrame::ListChildLists(FILE* aOut, const char* aPrefix,
     if (aSkippedListIDs.contains(listID)) {
       continue;
     }
-    fprintf_stderr(aOut, "%s%s %p <\n", aPrefix, ChildListName(listID),
-                   &GetChildList(listID));
+
+    // Use nsPrintfCString so that %p don't output prefix "0x". This is
+    // consistent with nsIFrame::ListTag().
+    const nsPrintfCString str("%s%s@%p <\n", aPrefix, ChildListName(listID),
+                              &GetChildList(listID));
+    fprintf_stderr(aOut, "%s", str.get());
+
     for (nsIFrame* kid : list) {
       kid->List(aOut, nestedPfx.get(), aFlags);
     }
diff --git a/layout/generic/nsLineBox.cpp b/layout/generic/nsLineBox.cpp
index f109bb760a88..5098697ea5af 100644
--- a/layout/generic/nsLineBox.cpp
+++ b/layout/generic/nsLineBox.cpp
@@ -237,7 +237,7 @@ void nsLineBox::List(FILE* out, const char* aPrefix,
                      nsIFrame::ListFlags aFlags) const {
   nsCString str(aPrefix);
   char cbuf[100];
-  str += nsPrintfCString("line %p: count=%d state=%s ",
+  str += nsPrintfCString("line@%p count=%d state=%s ",
                          static_cast<const void*>(this), GetChildCount(),
                          StateToString(cbuf, sizeof(cbuf)));
   if (IsBlock() && !GetCarriedOutBEndMargin().IsZero()) {