diff --git a/modules/libcom/src/osi/os/WIN32/epicsMath.h b/modules/libcom/src/osi/os/WIN32/epicsMath.h
index a7b4bca62..d0d02330f 100644
--- a/modules/libcom/src/osi/os/WIN32/epicsMath.h
+++ b/modules/libcom/src/osi/os/WIN32/epicsMath.h
@@ -19,12 +19,13 @@
 #define finite(D) _finite(D)
 #endif
 
-#ifndef __cplusplus
+#if !defined(__cplusplus) || (defined(_MSC_VER) && (_MSC_VER < 1800))
 
-/* these are macros in C but inline functions in C++
- * so ifndef does not work as a check in c++
- * and in a recent VS2022 update causes a conflict and
- * compile time error
+/* these are macros in C but usually inline functions in C++
+ * so macro ifndef does not work as a check in c++
+ * In a recent VS2022 update redefining as macros causes a conflict and
+ * compile time error. It looks like VS2013 and above supply
+ * isnan and isinf functions for in C++ so no need to create them
  */
 
 #ifndef isnan