1 files changed, 1 insertions, 1 deletions
diff --git a/src/MXF.h b/src/MXF.h
index d6e201a..30c1d16 100755
--- a/src/MXF.h
+++ b/src/MXF.h
@@ -253,7 +253,7 @@ namespace ASDCP
 	  }
 	  bool operator==(const PropertyType& rhs) const { return this->m_property == rhs; }
 	  bool operator==(const optional_property<PropertyType>& rhs) const { return this->m_property == rhs.m_property; }
-	  operator PropertyType&() { return this->m_property; }
+	  operator const PropertyType&() const { return this->m_property; }
 	  void set(const PropertyType& rhs) { this->m_property = rhs; this->m_has_value = true; }
 	  void set_has_value(bool has_value = true) { this->m_has_value = has_value; }
 	  void reset(const PropertyType& rhs) { this->m_has_value = false; }