diff --git a/indexer/string_file.cpp b/indexer/string_file.cpp
index 1b411f3340..1d3c976c07 100644
--- a/indexer/string_file.cpp
+++ b/indexer/string_file.cpp
@@ -56,21 +56,26 @@ void StringsFile::AddString(StringT const & s)
   m_strings.push_back(s);
 }
 
+bool StringsFile::IteratorT::IsEnd() const
+{
+  return m_file.m_queue.empty();
+}
+
 StringsFile::StringT StringsFile::IteratorT::dereference() const
 {
-  ASSERT ( !m_file.m_queue.empty(), () );
+  ASSERT ( IsValid(), () );
   return m_file.m_queue.top().m_string;
 }
 
 void StringsFile::IteratorT::increment()
 {
-  ASSERT ( !m_file.m_queue.empty(), () );
+  ASSERT ( IsValid(), () );
   int const index = m_file.m_queue.top().m_index;
 
   m_file.m_queue.pop();
 
   if (!m_file.PushNextValue(index))
-    m_end = m_file.m_queue.empty();
+    m_end = IsEnd();
 }
 
 StringsFile::StringsFile(string const & fPath)
diff --git a/indexer/string_file.hpp b/indexer/string_file.hpp
index 50acece3be..2dce71f103 100644
--- a/indexer/string_file.hpp
+++ b/indexer/string_file.hpp
@@ -60,14 +60,20 @@ public:
     StringsFile & m_file;
     bool m_end;
 
+    bool IsEnd() const;
+    inline bool IsValid() const { return (!m_end && !IsEnd()); }
+
   public:
     IteratorT(StringsFile & file, bool isEnd)
       : m_file(file), m_end(isEnd)
     {
+      // Additional check in case for empty sequence.
+      if (!m_end)
+        m_end = IsEnd();
     }
 
     StringT dereference() const;
-    bool equal(IteratorT const & r) const { return m_end == r.m_end; }
+    bool equal(IteratorT const & r) const { return (m_end == r.m_end); }
     void increment();
   };