diff --git a/opm/core/wells/wells.c b/opm/core/wells/wells.c
index 81a8ddc1..67ff1438 100644
--- a/opm/core/wells/wells.c
+++ b/opm/core/wells/wells.c
@@ -536,6 +536,8 @@ clone_wells(const struct Wells *W)
         }
     }
 
+    assert (wells_equal(newWells, W, false));
+
     return newWells;
 }