-const std::string GDCM_UNKNOWN = "gdcm::Unknown";
-const std::string GDCM_UNFOUND = "gdcm::Unfound";
-const std::string GDCM_BINLOADED = "gdcm::Binary data loaded";
-const std::string GDCM_NOTLOADED = "gdcm::NotLoaded";
-const std::string GDCM_UNREAD = "gdcm::UnRead";
+GDCM_EXPORT extern const std::string GDCM_UNKNOWN;
+GDCM_EXPORT extern const std::string GDCM_UNFOUND;
+GDCM_EXPORT extern const std::string GDCM_BINLOADED;
+GDCM_EXPORT extern const std::string GDCM_NOTLOADED;
+GDCM_EXPORT extern const std::string GDCM_UNREAD;