diff --git a/src/libCom/calc/calcPerform.c b/src/libCom/calc/calcPerform.c
index 459c9fb2d..c64bb37c1 100644
--- a/src/libCom/calc/calcPerform.c
+++ b/src/libCom/calc/calcPerform.c
@@ -104,8 +104,7 @@
 #include	<stddef.h>
 #include	<stdio.h>
 #include	<string.h>
-#include	<math.h>
-#include	<epicsMath.h>
+#include	"epicsMath.h"
 
 #include	"dbDefs.h"
 
@@ -512,7 +511,7 @@ printf ("*FINISHED*\n");
 		*presult = *pstacktop;
 	else
 		return(-1);
-	return((epicsIsNAN(*presult) ? -1 : 0));
+	return(((isnan(*presult)||isinf(*presult)) ? -1 : 0));
 }
 
 
diff --git a/src/libCom/calc/sCalcPerform.c b/src/libCom/calc/sCalcPerform.c
index b7c53dbf6..686fb683d 100644
--- a/src/libCom/calc/sCalcPerform.c
+++ b/src/libCom/calc/sCalcPerform.c
@@ -62,11 +62,10 @@
 #include	<stdlib.h>
 #include	<stdio.h>
 #include	<string.h>
-#include	<math.h>
+#include	"epicsMath.h"
 
 #include	"dbDefs.h"
 #define epicsExportSharedSymbols
-#include    "epicsMath.h"
 #include	"cvtFast.h"
 #include	"sCalcPostfix.h"
 #include	"sCalcPostfixPvt.h"
@@ -142,10 +141,13 @@ static void to_string(struct stackElement *ps)
 {
 	ps->s = calloc(20, 1);
 	/* any precision greater than 8 results in (slow) sprintf call */
-	if (epicsIsNAN(ps->d))
-		strcpy(ps->s,"NaN");
-	else
+	if (isnan(ps->d)) {
+		strcpy(ps->s,"nan");
+	} else if (isinf(ps->d)) {
+		strcpy(ps->s,"inf");
+	} else {
 		(void)cvtDoubleToString(ps->d, ps->s, 8);
+	}
 }
 
 static char *findConversionIndicator(char *s)
@@ -637,10 +639,13 @@ printf(") \n");
 #endif
 		*presult = *pd;
 		if (psresult && (lenSresult > 15)) {
-			if (epicsIsNAN(*pd))
-				strcpy(psresult,"NaN");
-			else
+			if (isnan(*pd)) {
+				strcpy(psresult,"nan");
+			} else if (isinf(*pd)) {
+				strcpy(psresult,"inf");
+			} else {
 				(void)cvtDoubleToString(*pd, psresult, 8);
+			}
 		}
 	} else {
 
@@ -1418,7 +1423,7 @@ printf(") \n");
 
 	} /* if (*post++ != USES_STRING) {} else */
 
-	return(0);
+	return(((isnan(*presult)||isinf(*presult)) ? -1 : 0));
 }
 
 
diff --git a/src/libCom/osi/os/VMS/epicsMath.h b/src/libCom/osi/os/VMS/epicsMath.h
new file mode 100644
index 000000000..88c95b24f
--- /dev/null
+++ b/src/libCom/osi/os/VMS/epicsMath.h
@@ -0,0 +1,7 @@
+#ifndef epicsMathh
+#define epicsMathh
+
+#include <math.h>
+#define isinf(D) 0
+
+#endif /* epicsMathh */
diff --git a/src/libCom/osi/os/WIN32/epicsMath.h b/src/libCom/osi/os/WIN32/epicsMath.h
index da4a8a2c3..8b9fc3a0f 100644
--- a/src/libCom/osi/os/WIN32/epicsMath.h
+++ b/src/libCom/osi/os/WIN32/epicsMath.h
@@ -2,8 +2,10 @@
 #ifndef epicsMathh
 #define epicsMathh
 
+#include <math.h>
 #include <float.h>
 
-#define epicsIsNAN(D) _isnan(D)
+#define isnan(D) _isnan(D)
+#define isinf(D) _isinf(D)
 
 #endif /* epicsMathh */
diff --git a/src/libCom/osi/os/posix/epicsMath.h b/src/libCom/osi/os/posix/epicsMath.h
index bb8ce4fd8..5b3e0076f 100644
--- a/src/libCom/osi/os/posix/epicsMath.h
+++ b/src/libCom/osi/os/posix/epicsMath.h
@@ -1,9 +1,6 @@
-
 #ifndef epicsMathh
 #define epicsMathh
 
 #include <math.h>
 
-#define epicsIsNAN(D) isnan(D)
-
 #endif /* epicsMathh */
diff --git a/src/libCom/osi/os/solaris/epicsMath.h b/src/libCom/osi/os/solaris/epicsMath.h
new file mode 100644
index 000000000..3f97b589b
--- /dev/null
+++ b/src/libCom/osi/os/solaris/epicsMath.h
@@ -0,0 +1,10 @@
+#ifndef epicsMathh
+#define epicsMathh
+
+#include <math.h>
+
+#include <ieeefp.h>
+#define isinf(x) (((x)==(x)) && !finite((x)))
+/* same as (!isnan(x) && !finite(x)) */
+
+#endif /* epicsMathh */
diff --git a/src/libCom/osi/os/vxWorks/epicsMath.h b/src/libCom/osi/os/vxWorks/epicsMath.h
index fa84e53de..c711a5702 100644
--- a/src/libCom/osi/os/vxWorks/epicsMath.h
+++ b/src/libCom/osi/os/vxWorks/epicsMath.h
@@ -2,8 +2,10 @@
 #ifndef epicsMathh
 #define epicsMathh
 
+#include <math.h>
 #include <private/mathP.h>
 
-#define epicsIsNAN(D) isNan(D)
+#define isnan(D) isNan(D)
+#define isinf(D) isInf(D)
 
 #endif /* epicsMathh */
diff --git a/src/libCom/test/Makefile b/src/libCom/test/Makefile
index de637d516..8cfa28478 100644
--- a/src/libCom/test/Makefile
+++ b/src/libCom/test/Makefile
@@ -13,6 +13,10 @@ epicsAlgorithmTest_SRCS += epicsAlgorithmTest.cpp
 PROD_HOST += epicsAlgorithmTest
 OBJS_IOC += epicsAlgorithmTest
 
+epicsMathTestHost_SRCS += epicsMathTestMain.cpp epicsMathTest.c
+PROD_HOST += epicsMathTestHost
+OBJS_IOC += epicsMathTest
+
 epicsTimeTestHost_SRCS += epicsTimeTestMain.cpp epicsTimeTest.cpp
 PROD_HOST += epicsTimeTestHost
 OBJS_IOC += epicsTimeTest
diff --git a/src/libCom/test/epicsMathTest.c b/src/libCom/test/epicsMathTest.c
new file mode 100644
index 000000000..2b2d8fc4e
--- /dev/null
+++ b/src/libCom/test/epicsMathTest.c
@@ -0,0 +1,35 @@
+/* epicsMathTest.c
+ *
+ *      Author  Marty Kraimer
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <stddef.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "epicsMath.h"
+
+static char *truth[2] = {"false","true"};
+
+void epicsMathTest ()
+{
+    double a,b,c;
+
+    a=0.0; b=0.0; c=a/b;
+    printf("a %e b %e c %e isnan %s isinf %s\n",
+        a,b,c,truth[isnan(c) ? 1 : 0],truth[isinf(c) ? 1 : 0]);
+    a=1e300; b=1e-300; c=a/b;
+    printf("a %e b %e c %e isnan %s isinf %s\n",
+        a,b,c,truth[isnan(c) ? 1 : 0],truth[isinf(c) ? 1 : 0]);
+    a=-1e300; b=1e-300; c=a/b;
+    printf("a %e b %e c %e isnan %s isinf %s\n",
+        a,b,c,truth[isnan(c) ? 1 : 0],truth[isinf(c) ? 1 : 0]);
+    a=0.0; b=1.0; c=a/b;
+    printf("a %e b %e c %e isnan %s isinf %s\n",
+        a,b,c,truth[isnan(c) ? 1 : 0],truth[isinf(c) ? 1 : 0]);
+    a=1e300; b=1e300; c=a/b;
+    printf("a %e b %e c %e isnan %s isinf %s\n",
+        a,b,c,truth[isnan(c) ? 1 : 0],truth[isinf(c) ? 1 : 0]);
+}
diff --git a/src/libCom/test/epicsMathTestMain.cpp b/src/libCom/test/epicsMathTestMain.cpp
new file mode 100644
index 000000000..c57010377
--- /dev/null
+++ b/src/libCom/test/epicsMathTestMain.cpp
@@ -0,0 +1,14 @@
+/* epicsMathTestMain.cpp
+ *
+ *      Author  Marty Kraimer
+ */
+
+extern "C" {
+void epicsMathTest ( void );
+}
+
+int main ( int  , char *[] )
+{
+    epicsMathTest ();
+    return 0;
+}