diff --git a/dlls/d3dx9_36/tests/mesh.c b/dlls/d3dx9_36/tests/mesh.c
index 21c3b4148c3..47a1b1fa975 100644
--- a/dlls/d3dx9_36/tests/mesh.c
+++ b/dlls/d3dx9_36/tests/mesh.c
@@ -26,6 +26,16 @@
 #include "wine/test.h"
 #include "d3dx9.h"
 
+#ifndef NAN
+/* From wine/port.h */
+static inline float __port_nan(void)
+{
+    static const unsigned __nan_bytes = 0x7fc00000;
+    return *(const float *)&__nan_bytes;
+}
+#define NAN __port_nan()
+#endif
+
 /* Set the WINETEST_DEBUG environment variable to be greater than 1 for verbose
  * function call traces of ID3DXAllocateHierarchy callbacks. */
 #define TRACECALLBACK if(winetest_debug > 1) trace