diff --git a/MultiSource/Benchmarks/DOE-ProxyApps-C++/CLAMR/clamr_cpuonly.cpp b/MultiSource/Benchmarks/DOE-ProxyApps-C++/CLAMR/clamr_cpuonly.cpp
index e3e5af0..ced2fe4 100644
--- a/MultiSource/Benchmarks/DOE-ProxyApps-C++/CLAMR/clamr_cpuonly.cpp
+++ b/MultiSource/Benchmarks/DOE-ProxyApps-C++/CLAMR/clamr_cpuonly.cpp
@@ -55,7 +55,7 @@
  */
 
 #include <algorithm>
-#include <math.h>
+#include <cmath>
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/time.h>
@@ -499,7 +499,7 @@
 
    int error_status = STATUS_OK;
 
-   if (isnan(H_sum)) {
+   if (std::isnan(H_sum)) {
       printf("Got a NAN on cycle %d\n",ncycle);
       error_status = STATUS_NAN;
    }