diff --git a/src/soca/ExplicitDiffusion/ExplicitDiffusion.cc b/src/soca/ExplicitDiffusion/ExplicitDiffusion.cc
index 5353a37f4..16e790221 100644
--- a/src/soca/ExplicitDiffusion/ExplicitDiffusion.cc
+++ b/src/soca/ExplicitDiffusion/ExplicitDiffusion.cc
@@ -57,7 +57,7 @@ void ExplicitDiffusion::multiply(oops::FieldSet3D & fset) const {
 
 // --------------------------------------------------------------------------------------
 
-void ExplicitDiffusion::directCalibration(const std::vector<oops::FieldSet3D> &) {
+void ExplicitDiffusion::directCalibration(const oops::FieldSets &) {
   eckit::LocalConfiguration conf = (*params_.calibration.value()).toConfiguration();
   soca_explicitdiffusion_calibrate_f90(keyFortran_, &conf);
 }
diff --git a/src/soca/ExplicitDiffusion/ExplicitDiffusion.h b/src/soca/ExplicitDiffusion/ExplicitDiffusion.h
index 9ab727c4b..6aad31d88 100644
--- a/src/soca/ExplicitDiffusion/ExplicitDiffusion.h
+++ b/src/soca/ExplicitDiffusion/ExplicitDiffusion.h
@@ -42,7 +42,7 @@ class ExplicitDiffusion : public saber::SaberCentralBlockBase {
   void randomize(oops::FieldSet3D &) const override;
   void multiply(oops::FieldSet3D &) const override;
 
-  void directCalibration(const std::vector<oops::FieldSet3D> &) override;
+  void directCalibration(const oops::FieldSets &) override;
   void read() override;
   void write() const override;