diff --git a/dumux/material/fluidsystems/brineco2.hh b/dumux/material/fluidsystems/brineco2.hh
index 15015f1c9ae8b43411466de08c485a14d940518a..9c8cbe0faf93f4747204828b5ae7be86206be5ac 100644
--- a/dumux/material/fluidsystems/brineco2.hh
+++ b/dumux/material/fluidsystems/brineco2.hh
@@ -87,9 +87,8 @@ public:
     static const int nCompIdx = 1;
     static const int lCompIdx = wCompIdx;
     static const int gCompIdx = nCompIdx;
-
-    static const int BrineIdx = 0;
-    static const int CO2Idx = 1;
+    static const int BrineIdx = wCompIdx;
+    static const int CO2Idx = nCompIdx;
 
     /*!
      * \brief Return the human readable name of a fluid phase
diff --git a/dumux/material/fluidsystems/h2oair.hh b/dumux/material/fluidsystems/h2oair.hh
index fee6071aa82550dcbd4267fc5d11b4f0bd3cadcc..b8f97aae28b2ac6533d6feffb75de81841d4559a 100644
--- a/dumux/material/fluidsystems/h2oair.hh
+++ b/dumux/material/fluidsystems/h2oair.hh
@@ -215,8 +215,8 @@ public:
     //! Number of components in the fluid system
     static constexpr int numComponents = 2;
 
-    static constexpr int H2OIdx = 0;
-    static constexpr int AirIdx = 1;
+    static constexpr int H2OIdx = wCompIdx;
+    static constexpr int AirIdx = nCompIdx;
 
     /*!
      * \brief Return the human readable name of a component
diff --git a/dumux/material/fluidsystems/h2on2.hh b/dumux/material/fluidsystems/h2on2.hh
index daa0d27a8ab74d276d542a98b3bb9942024e665d..ec45271609c1f98be061c418c79e556029eee81a 100644
--- a/dumux/material/fluidsystems/h2on2.hh
+++ b/dumux/material/fluidsystems/h2on2.hh
@@ -183,8 +183,8 @@ public:
     //! Number of components in the fluid system
     static constexpr int numComponents = 2;
 
-    static constexpr int H2OIdx = 0;
-    static constexpr int N2Idx = 1;
+    static constexpr int H2OIdx = wCompIdx;
+    static constexpr int N2Idx = nCompIdx;
 
     //! The components for pure water
     typedef TabulatedH2O H2O;
diff --git a/dumux/material/fluidsystems/purewatersimple.hh b/dumux/material/fluidsystems/purewatersimple.hh
index f411f798bfa3d2df666f94d9a10f870c61e253ad..b2a9f3d4e8c5d9678bae580159aaad84512ff931 100644
--- a/dumux/material/fluidsystems/purewatersimple.hh
+++ b/dumux/material/fluidsystems/purewatersimple.hh
@@ -184,8 +184,8 @@ public:
     //! Number of components in the fluid system
     static constexpr int numComponents = 2;
 
-    static constexpr int H2OIdx = 0;
-    static constexpr int N2Idx = 1;
+    static constexpr int H2OIdx = wCompIdx;
+    static constexpr int N2Idx = nCompIdx;
 
     //! The components for pure water
     typedef SimpleH2O H2O;