diff --git a/modules/geom/src/vec3.hh b/modules/geom/src/vec3.hh
index dc35a07ec842584e547419d794682ed55cea6363..4d139a3211980d7a41c656c97d9b323e2fb69e92 100644
--- a/modules/geom/src/vec3.hh
+++ b/modules/geom/src/vec3.hh
@@ -196,7 +196,7 @@ inline std::ostream& operator<<(std::ostream& os, const Vec3& v)
 
 namespace geom {
 
-class Vec3List : public std::vector<Vec3> {
+class DLLEXPORT_OST_GEOM Vec3List : public std::vector<Vec3> {
 public:
   typedef std::vector<Vec3> base_type;
   Vec3List() : base_type() {}