diff --git a/dumux/geomechanics/el1p2c/model.hh b/dumux/geomechanics/el1p2c/model.hh
index add0dbf5764b198eaaa2119dbfeacaa668eab3fd..9998cc7fcf6b44105f1c8b9df69f3a2fd9b23078 100644
--- a/dumux/geomechanics/el1p2c/model.hh
+++ b/dumux/geomechanics/el1p2c/model.hh
@@ -398,7 +398,7 @@ public:
 
             for (int i = 0; i < dim; i++)
                 {
-                    if (isnan(eigenValues[i]))
+                    if (std::isnan(eigenValues[i]))
                         eigenValues[i] = 0.0;
                 }
 
diff --git a/dumux/geomechanics/el2p/model.hh b/dumux/geomechanics/el2p/model.hh
index fd71aec13426b3f4dd4b86ec136bb07a2bac1077..7cca7f6ca6e49ce8968d8812ebd2e82a1b1d47cf 100644
--- a/dumux/geomechanics/el2p/model.hh
+++ b/dumux/geomechanics/el2p/model.hh
@@ -550,7 +550,7 @@ public:
 
             for (int i = 0; i < dim; i++)
                 {
-                    if (isnan(eigenValues[i]))
+                    if (std::isnan(eigenValues[i]))
                         eigenValues[i] = 0.0;
                 }
 
diff --git a/dumux/porousmediumflow/2p/sequential/diffusion/mpfa/lmethod/3dtransmissibilitycalculator.hh b/dumux/porousmediumflow/2p/sequential/diffusion/mpfa/lmethod/3dtransmissibilitycalculator.hh
index 01240bbaf59df599d9aec1a510bc791e82686047..ca1f97f6fe07a537962ce016aab8f6ba96d2360b 100644
--- a/dumux/porousmediumflow/2p/sequential/diffusion/mpfa/lmethod/3dtransmissibilitycalculator.hh
+++ b/dumux/porousmediumflow/2p/sequential/diffusion/mpfa/lmethod/3dtransmissibilitycalculator.hh
@@ -957,7 +957,7 @@ int FvMpfaL3dTransmissibilityCalculator<TypeTag>::transmissibilityCaseOne(
 
     transmissibility = D;
 
-    if (isnan(transmissibility.frobenius_norm()))
+    if (std::isnan(transmissibility.frobenius_norm()))
     {
         std::cout<<"idx: "<<idx1<<idx2<<idx3<<idx5<<"\n";
 
@@ -1352,7 +1352,7 @@ int FvMpfaL3dTransmissibilityCalculator<TypeTag>::transmissibilityCaseTwo(
 
     transmissibility = D;
 
-    if (isnan(transmissibility.frobenius_norm()))
+    if (std::isnan(transmissibility.frobenius_norm()))
     {
         std::cout<<"idx: "<<idx1<<idx2<<idx4<<idx6<<"\n";
 
@@ -1748,7 +1748,7 @@ int FvMpfaL3dTransmissibilityCalculator<TypeTag>::transmissibilityCaseThree(
 
     transmissibility = D;
 
-    if (isnan(transmissibility.frobenius_norm()))
+    if (std::isnan(transmissibility.frobenius_norm()))
     {
         std::cout<<"case 3: transmissibility = "<<transmissibility<<"\n";
         std::cout<<"globalPos1 = "<<globalPos1<<"\n";
@@ -2145,7 +2145,7 @@ int FvMpfaL3dTransmissibilityCalculator<TypeTag>::transmissibilityCaseFour(
 
     transmissibility = D;
 
-    if (isnan(transmissibility.frobenius_norm()))
+    if (std::isnan(transmissibility.frobenius_norm()))
     {
         std::cout<<"case 4: transmissibility = "<<transmissibility<<"\n";
 
diff --git a/dumux/porousmediumflow/2p/sequential/diffusion/mpfa/omethod/2dpressure.hh b/dumux/porousmediumflow/2p/sequential/diffusion/mpfa/omethod/2dpressure.hh
index 8077e3339644aa152d5438e53af6c9e17d39d814..23a4cc1c294e2c942509ead6f2135b8dae486da9 100644
--- a/dumux/porousmediumflow/2p/sequential/diffusion/mpfa/omethod/2dpressure.hh
+++ b/dumux/porousmediumflow/2p/sequential/diffusion/mpfa/omethod/2dpressure.hh
@@ -1550,7 +1550,7 @@ void FvMpfaO2dPressure2p<TypeTag>::assemble()
                 pcFluxReal[2] *= fracFlow34;
                 pcFluxReal[3] *= fracFlow14;
 
-//                if (isnan(pcFluxReal.two_norm()))
+//                if (std::isnan(pcFluxReal.two_norm()))
 //                                std::cout<<"pcFlux = "<<pcFlux<<"\n";
 
                 switch (pressureType_)