diff --git a/RecoEgamma/PhotonIdentification/src/PhotonMVABasedHaloTagger.cc b/RecoEgamma/PhotonIdentification/src/PhotonMVABasedHaloTagger.cc
index afaffacd73b56..5013aa5111f84 100644
--- a/RecoEgamma/PhotonIdentification/src/PhotonMVABasedHaloTagger.cc
+++ b/RecoEgamma/PhotonIdentification/src/PhotonMVABasedHaloTagger.cc
@@ -89,7 +89,7 @@ double PhotonMVABasedHaloTagger::calculateMVA(const reco::Photon* pho,
   ////set all the above calculated variables as input to the MVA
 
   const auto& vCov = lazyToolnoZS.localCovariances(*(pho->superCluster()->seed()));
-  double spp = (isnan(vCov[2]) ? 0. : sqrt(vCov[2]));
+  double spp = (std::isnan(vCov[2]) ? 0. : sqrt(vCov[2]));
 
   ///https://cmssdt.cern.ch/lxr/source/RecoEgamma/ElectronIdentification/src/ElectronMVAEstimator.cc
 
diff --git a/Validation/MtdValidation/plugins/Primary4DVertexValidation.cc b/Validation/MtdValidation/plugins/Primary4DVertexValidation.cc
index 833c4647bff43..7c72fe24ed209 100644
--- a/Validation/MtdValidation/plugins/Primary4DVertexValidation.cc
+++ b/Validation/MtdValidation/plugins/Primary4DVertexValidation.cc
@@ -1323,7 +1323,7 @@ void Primary4DVertexValidation::analyze(const edm::Event& iEvent, const edm::Eve
               unsigned int noPIDtype = 0;
               if (probPi[*iTrack] == -1) {
                 noPIDtype = 1;
-              } else if (isnan(probPi[*iTrack])) {
+              } else if (std::isnan(probPi[*iTrack])) {
                 noPIDtype = 2;
               } else if (probPi[*iTrack] == 1 && probK[*iTrack] == 0 && probP[*iTrack] == 0) {
                 noPIDtype = 3;