1 files changed, 13 insertions, 0 deletions
diff --git a/missing/isnan.c b/missing/isnan.c
index 96bb93ba6a..3c56765807 100644
--- a/missing/isnan.c
+++ b/missing/isnan.c
@@ -1,3 +1,15 @@
+#ifdef _MSC_VER
+
+#include <float.h>
+int
+isnan(n)
+  double n;
+{
+  return _isnan(n);
+}
+
+#else
+
 static int double_ne();
 
 int
@@ -14,3 +26,4 @@ double_ne(n1, n2)
 {
   return n1 != n2;
 }
+#endif