diff --git a/src/common/mm_io.cpp b/src/common/mm_io.cpp
index 047cb5e4e..1829ddbf5 100644
--- a/src/common/mm_io.cpp
+++ b/src/common/mm_io.cpp
@@ -554,7 +554,7 @@ mm_io_c::write_bom(const std::string &charset) {
   const unsigned char *bom;
   unsigned int bom_len;
 
-  if (charset.empty())
+  if (m_bom_written || charset.empty())
     return false;
 
   if ((charset =="UTF-8") || (charset =="UTF8")) {
@@ -577,7 +577,15 @@ mm_io_c::write_bom(const std::string &charset) {
 
   setFilePointer(0, seek_beginning);
 
-  return (write(bom, bom_len) == bom_len);
+  m_bom_written = write(bom, bom_len) == bom_len;
+
+  return m_bom_written;
+}
+
+bool
+mm_io_c::bom_written()
+  const {
+  return m_bom_written;
 }
 
 int64_t
diff --git a/src/common/mm_io.h b/src/common/mm_io.h
index b8ec6441b..176a1f119 100644
--- a/src/common/mm_io.h
+++ b/src/common/mm_io.h
@@ -30,7 +30,7 @@ typedef std::shared_ptr<charset_converter_c> charset_converter_cptr;
 
 class mm_io_c: public IOCallback {
 protected:
-  bool m_dos_style_newlines;
+  bool m_dos_style_newlines, m_bom_written;
   std::stack<int64_t> m_positions;
   int64_t m_current_position, m_cached_size;
   charset_converter_cptr m_string_output_converter;
@@ -38,6 +38,7 @@ protected:
 public:
   mm_io_c()
     : m_dos_style_newlines(false)
+    , m_bom_written{}
     , m_current_position(0)
     , m_cached_size(-1)
   {
@@ -91,6 +92,7 @@ public:
     return puts(format.str());
   }
   virtual bool write_bom(const std::string &charset);
+  virtual bool bom_written() const;
   virtual int getch();
 
   virtual void save_pos(int64_t new_pos = -1);