diff --git a/dumux/material/fluidsystems/3pimmiscible.hh b/dumux/material/fluidsystems/3pimmiscible.hh
index 4914eb2576baf9928cd16ca3ee1317de738f4eb1..b7285ac81d05eef634ce97ee09066b86c22e31c7 100644
--- a/dumux/material/fluidsystems/3pimmiscible.hh
+++ b/dumux/material/fluidsystems/3pimmiscible.hh
@@ -121,7 +121,7 @@ public:
             case wPhaseIdx: return WettingFluid::isGas(); break;
             case nPhaseIdx: return NonwettingFluid::isGas(); break;
             case gPhaseIdx: return Gas::isGas(); break;
-            default: DUNE_THROW(Dune::InvalidStateException, "Invalid phase index");
+            default: return false; // TODO: constexpr-compatible throw
         }
     }
 
@@ -160,7 +160,7 @@ public:
             case wPhaseIdx: return WettingFluid::isCompressible(); break;
             case nPhaseIdx: return NonwettingFluid::isCompressible(); break;
             case gPhaseIdx: return Gas::isCompressible(); break;
-            default: DUNE_THROW(Dune::InvalidStateException, "Invalid phase index");
+            default: return false; // TODO: constexpr-compatible throw
         }
     }
 
@@ -180,7 +180,7 @@ public:
             case wPhaseIdx: return WettingFluid::isIdealGas(); break;
             case nPhaseIdx: return NonwettingFluid::isIdealGas(); break;
             case gPhaseIdx: return Gas::isIdealGas(); break;
-            default: DUNE_THROW(Dune::InvalidStateException, "Invalid phase index");
+            default: return false; // TODO: constexpr-compatible throw
         }
     }