diff --git a/src/simulation/RunEvent.cpp b/src/simulation/RunEvent.cpp
index 2cf25aa6..65a84e30 100755
--- a/src/simulation/RunEvent.cpp
+++ b/src/simulation/RunEvent.cpp
@@ -557,7 +557,7 @@ void RunEvent::processStaticFailure(Simulation *sim) {
             //
             // yoder: as per request by KS, change std::isnan() --> std::isnan(); std::isnan() appears to throw an error on some platforms.
             // Eric: Probably don't need this if check
-            if (std::isnan(s_it->_shear_final) and std::isnan(s_it->_normal_final)) {
+            if (isnan(s_it->_shear_final) and isnan(s_it->_normal_final)) {
                 // note: the stress entries are initialized with nan values, but if there are cases where non nan values need to be updated,
                 // this logic should be revisited.
                 event_sweeps.setFinalStresses(sweep_num,
diff --git a/src/simulation/SanityCheck.cpp b/src/simulation/SanityCheck.cpp
index 013bcce9..a8758870 100755
--- a/src/simulation/SanityCheck.cpp
+++ b/src/simulation/SanityCheck.cpp
@@ -35,7 +35,7 @@ bool SanityCheck::assertCFFValueCorrectness(Simulation *sim) {
         gid = sim->getGlobalBID(lid);
         double val = sim->getCFF(gid);
 
-        if (std::isnan(val) || fabs(val) > 1e20) {
+        if (isnan(val) || fabs(val) > 1e20) {
             failed_cffs.push_back(std::make_pair(gid, val));
             failed = true;
         }
@@ -53,7 +53,7 @@ bool SanityCheck::assertUpdateFieldCorrectness(Simulation *sim) {
         gid = sim->getGlobalBID(lid);
         double val = sim->getUpdateField(gid);
 
-        if (std::isnan(val) || fabs(val) > 1e20) {
+        if (isnan(val) || fabs(val) > 1e20) {
             failed_update_fields.push_back(std::make_pair(gid, val));
             failed = true;
         }
diff --git a/src/simulation/UpdateBlockStress.cpp b/src/simulation/UpdateBlockStress.cpp
index 61c98703..969d3aff 100755
--- a/src/simulation/UpdateBlockStress.cpp
+++ b/src/simulation/UpdateBlockStress.cpp
@@ -98,7 +98,7 @@ void UpdateBlockStress::init(SimFramework *_sim) {
     // And update the slip deficit on each process to take this into account
     for (gid=0; gid<sim->numGlobalBlocks(); ++gid) {
         // If we haven't loaded slip deficits, updateField is NaN so set slip deficit to zero in that case
-        sim->setSlipDeficit(gid, std::isnan(sim->getUpdateField(gid)) ? 0.0 : sim->getUpdateField(gid));
+        sim->setSlipDeficit(gid, isnan(sim->getUpdateField(gid)) ? 0.0 : sim->getUpdateField(gid));
         //std::cout << gid << "  slip deficit: " << sim->getSlipDeficit(gid) << std::endl;
     }