diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index fafc852a4f3..6c8b41d2a91 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -15,6 +15,9 @@
 #include "postgres.h"
 
 #include <ctype.h>
+#ifdef _MSC_VER
+#include <float.h>				/* for _isnan */
+#endif
 #include <math.h>
 
 #include "access/htup_details.h"