diff --git a/prism/defines.h b/prism/defines.h
index 785361728e..80db39bc77 100644
--- a/prism/defines.h
+++ b/prism/defines.h
@@ -136,6 +136,14 @@
 #   define PRISM_HAS_FILESYSTEM
 #endif
 
+/**
+ * isinf on POSIX systems it accepts a float, a double, or a long double.
+ * But Windows didn't provide isinf, so we need to use _finite instead.
+ */
+#ifdef _WIN32
+#   include <float.h>
+#endif
+
 /**
  * If you build prism with a custom allocator, configure it with
  * "-D PRISM_XALLOCATOR" to use your own allocator that defines xmalloc,