diff --git a/src/singledocparser.cpp b/src/singledocparser.cpp
index a27c1c3..1b4262e 100644
--- a/src/singledocparser.cpp
+++ b/src/singledocparser.cpp
@@ -46,6 +46,8 @@ void SingleDocParser::HandleDocument(EventHandler& eventHandler) {
 }
 
 void SingleDocParser::HandleNode(EventHandler& eventHandler) {
+  assert(depth < depth_limit);
+  depth++;
   // an empty node *is* a possibility
   if (m_scanner.empty()) {
     eventHandler.OnNull(m_scanner.mark(), NullAnchor);
diff --git a/src/singledocparser.h b/src/singledocparser.h
index 2b92067..7046f1e 100644
--- a/src/singledocparser.h
+++ b/src/singledocparser.h
@@ -51,6 +51,8 @@ class SingleDocParser : private noncopyable {
   anchor_t LookupAnchor(const Mark& mark, const std::string& name) const;
 
  private:
+  int depth = 0;
+  int depth_limit = 2000;
   Scanner& m_scanner;
   const Directives& m_directives;
   std::unique_ptr<CollectionStack> m_pCollectionStack;