diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index f4ddc7647..c36aaaa63 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -13876,9 +13876,15 @@ DocShellOriginAttributes
 nsDocShell::GetOriginAttributes()
 {
   DocShellOriginAttributes attrs;
+  nsCOMPtr<nsIDocument> doc;
+
+  // It is possible to have a null document. If so, act as if we are
+  // the topmost docshell, since this usually occurs on shutdown.
   RefPtr<nsDocShell> parent = GetParentDocshell();
-  if (parent) {
-    nsCOMPtr<nsIPrincipal> parentPrin = parent->GetDocument()->NodePrincipal();
+  if (MOZ_LIKELY(parent))
+    doc = parent->GetDocument();
+  if (MOZ_LIKELY(doc)) {
+    nsCOMPtr<nsIPrincipal> parentPrin = doc->NodePrincipal();
     PrincipalOriginAttributes poa = BasePrincipal::Cast(parentPrin)->OriginAttributesRef();
     attrs.InheritFromDocToChildDocShell(poa);
   } else {
diff --git a/js/src/vm/String.cpp b/js/src/vm/String.cpp
index 22336bd36..37ad492d4 100644
--- a/js/src/vm/String.cpp
+++ b/js/src/vm/String.cpp
@@ -681,7 +681,7 @@ JSDependentString::dumpRepresentation(FILE* fp, int indent) const
     indent += 2;
 
     if (mozilla::Maybe<size_t> offset = baseOffset())
-        fprintf(fp, "%*soffset: %" PRIuSIZE "\n", indent, "", *offset);
+        fprintf(fp, "%*soffset: %zu\n", indent, "", *offset);
 
     fprintf(fp, "%*sbase: ", indent, "");
     base()->dumpRepresentation(fp, indent);