diff --git a/opm/simulators/aquifers/AquiferConstantFlux.hpp b/opm/simulators/aquifers/AquiferConstantFlux.hpp
index 14769cbf3..ed768a6d0 100644
--- a/opm/simulators/aquifers/AquiferConstantFlux.hpp
+++ b/opm/simulators/aquifers/AquiferConstantFlux.hpp
@@ -113,7 +113,7 @@ public:
 
     void addToSource(RateVector& rates,
                      const unsigned cellIdx,
-                     const unsigned timeIdx) override
+                     [[maybe_unused]] const unsigned timeIdx) override
     {
         const int idx = this->cellToConnectionIdx_[cellIdx];
         if (idx < 0) {