diff --git a/exercises/exercise-biomineralization/biominspatialparams.hh b/exercises/exercise-biomineralization/biominspatialparams.hh
index a4dd38ac1248889362d3e5624aa7a24b7bbc968a..c8d01efc71a2bcb7b63c87d7111a6f58a72fc14c 100644
--- a/exercises/exercise-biomineralization/biominspatialparams.hh
+++ b/exercises/exercise-biomineralization/biominspatialparams.hh
@@ -326,10 +326,10 @@ private:
     { return 2*phiInit - phiEvaluated;}
 
     bool isInAquitard_(const GlobalPosition &globalPos) const
-    { return globalPos[dimWorld-1] > 8 + eps_ && globalPos[dimWorld-1] < 10 + eps_;}
+    { return globalPos[dimWorld-1] > 8 - eps_ && globalPos[dimWorld-1] < 10 + eps_;}
 
     bool isFaultZone_(const GlobalPosition &globalPos) const
-    { return globalPos[dimWorld-2] > 1.5 + eps_ && globalPos[dimWorld-2] < 3 + eps_;}
+    { return globalPos[dimWorld-2] > 2 - eps_ && globalPos[dimWorld-2] < 3 + eps_;}
 
     using ModelTraits = typename GET_PROP_TYPE(TypeTag, ModelTraits);
     PorosityPrecipitation<Scalar, ModelTraits::numComponents(), ModelTraits::numSolidComps()> poroLaw_;