diff --git a/modules/gfx/src/bitmap_io.hh b/modules/gfx/src/bitmap_io.hh
index e8263d97f75aa47a1f3ad76dfdd9df10941477c2..dacb9dbe36b95a32c6d9b8273999ebbac7efe8eb 100644
--- a/modules/gfx/src/bitmap_io.hh
+++ b/modules/gfx/src/bitmap_io.hh
@@ -47,9 +47,9 @@ struct Bitmap
   boost::shared_array<unsigned char> data;
 };
 
-void ExportBitmap(const String& fname, std::string ext, unsigned int width, unsigned int height,unsigned char* data);
+void DLLEXPORT_OST_GFX ExportBitmap(const String& fname, std::string ext, unsigned int width, unsigned int height,unsigned char* data);
 
-Bitmap ImportBitmap(const String& fname, std::string ext="");
+Bitmap DLLEXPORT_OST_GFX ImportBitmap(const String& fname, std::string ext="");
 
 
 }} // ns