diff --git a/src/libCom/cppStd/epicsAlgorithm.h b/src/libCom/cppStd/epicsAlgorithm.h
index 54dec91e9..20850242d 100644
--- a/src/libCom/cppStd/epicsAlgorithm.h
+++ b/src/libCom/cppStd/epicsAlgorithm.h
@@ -13,9 +13,7 @@
 #ifndef __EPICS_ALGORITHM_H__
 #define __EPICS_ALGORITHM_H__
 
-#include <cmath>
-
-using std::isnan;
+#include "epicsMath.h"
 
 // The C++ standard only requires types to be less-than comparable, so
 // the epicsMin and epicsMax templates only use operator <
diff --git a/src/libCom/iocsh/iocsh.cpp b/src/libCom/iocsh/iocsh.cpp
index 307fabfbf..03d4c28b4 100644
--- a/src/libCom/iocsh/iocsh.cpp
+++ b/src/libCom/iocsh/iocsh.cpp
@@ -16,7 +16,6 @@
 #include <stdio.h>
 #include <ctype.h>
 #include <errno.h>
-#include <cmath>
 
 #define epicsExportSharedSymbols
 #include "errlog.h"
@@ -32,8 +31,6 @@
 #include "cantProceed.h"
 #include "iocsh.h"
 
-using std::isinf;
-
 extern "C" {
 
 /*
diff --git a/src/libCom/test/epicsAlgorithmTest.cpp b/src/libCom/test/epicsAlgorithmTest.cpp
index 108c15d62..fa8c0c03f 100644
--- a/src/libCom/test/epicsAlgorithmTest.cpp
+++ b/src/libCom/test/epicsAlgorithmTest.cpp
@@ -9,15 +9,11 @@
 // epicsAlgorithmTest.cpp
 //	Authors: Jeff Hill & Andrew Johnson
 
-#include <cmath>
-
 #include "epicsUnitTest.h"
 #include "epicsAlgorithm.h"
 #include "epicsMath.h"
 #include "testMain.h"
 
-using std::isnan;
-
 MAIN(epicsAlgorithm)
 {
     testPlan(22);
diff --git a/src/libCom/test/epicsCalcTest.cpp b/src/libCom/test/epicsCalcTest.cpp
index aae412262..2492c95ba 100644
--- a/src/libCom/test/epicsCalcTest.cpp
+++ b/src/libCom/test/epicsCalcTest.cpp
@@ -8,7 +8,6 @@
 
 #include <stdlib.h>
 #include <string.h>
-#include <cmath>
 
 #include "epicsUnitTest.h"
 #include "epicsTypes.h"
@@ -17,9 +16,6 @@
 #include "postfix.h"
 #include "testMain.h"
 
-using std::isnan;
-using std::isinf;
-
 /* Infrastructure for running tests */
 
 double doCalc(const char *expr) {