diff --git a/Modules/Learning/Sampling/include/otbSamplingRateCalculator.h b/Modules/Learning/Sampling/include/otbSamplingRateCalculator.h
index 04517fb15a736bf6ad46b372c156bcd575018515..c16a758a5d82b51578de112e59963470f3625f41 100644
--- a/Modules/Learning/Sampling/include/otbSamplingRateCalculator.h
+++ b/Modules/Learning/Sampling/include/otbSamplingRateCalculator.h
@@ -50,7 +50,7 @@ public:
   /** typdefs **/
   typedef std::map<std::string, unsigned long>  ClassCountMapType;
   typedef ClassCountMapType::const_iterator constItMapType;
-  typedef struct Triplet
+  typedef struct OTBSampling_EXPORT Triplet
    {
      unsigned long Required;
      unsigned long Tot;