diff --git a/ebos/eclgenerictracermodel.cc b/ebos/eclgenerictracermodel.cc
index 4081e981d..bcf4f1d22 100644
--- a/ebos/eclgenerictracermodel.cc
+++ b/ebos/eclgenerictracermodel.cc
@@ -134,6 +134,13 @@ setTracerConcentration(int tracerIdx, int globalDofIdx, Scalar value)
     this->tracerConcentration_[tracerIdx][globalDofIdx] = value;
 }
 
+template<class Grid,class GridView, class DofMapper, class Stencil, class Scalar>
+int EclGenericTracerModel<Grid,GridView,DofMapper,Stencil,Scalar>::
+numTracers() const
+{
+    return this->eclState_.tracer().size();
+}
+
 
 template<class Grid,class GridView, class DofMapper, class Stencil, class Scalar>
 void EclGenericTracerModel<Grid,GridView,DofMapper,Stencil,Scalar>::
diff --git a/ebos/eclgenerictracermodel.hh b/ebos/eclgenerictracermodel.hh
index 42dc4c6bf..95a7183b0 100644
--- a/ebos/eclgenerictracermodel.hh
+++ b/ebos/eclgenerictracermodel.hh
@@ -55,8 +55,7 @@ public:
     /*!
      * \brief Return the number of tracers considered by the tracerModel.
      */
-    int numTracers() const
-    { return tracerNames_.size(); }
+    int numTracers() const;
 
     /*!
      * \brief Return the tracer name