diff --git a/dll/directx/wine/wined3d/CMakeLists.txt b/dll/directx/wine/wined3d/CMakeLists.txt
index 57a800fd9b3..8e3f5bdb61f 100644
--- a/dll/directx/wine/wined3d/CMakeLists.txt
+++ b/dll/directx/wine/wined3d/CMakeLists.txt
@@ -8,6 +8,10 @@ include_directories(BEFORE ${REACTOS_SOURCE_DIR}/include/reactos/wine)
 
 set_rc_compiler()
 
+if(MSVC)
+    add_definitions(-Disnan=_isnan)
+endif()
+
 spec2def(wined3.dll wined3d.spec)
 
 list(APPEND SOURCE
diff --git a/dll/directx/wine/wined3d/surface_base.c b/dll/directx/wine/wined3d/surface_base.c
index d4e96ff2c46..e4dd853b0b3 100644
--- a/dll/directx/wine/wined3d/surface_base.c
+++ b/dll/directx/wine/wined3d/surface_base.c
@@ -43,7 +43,7 @@ static inline unsigned short float_32_to_16(const float *in)
 
     /* Deal with special numbers */
     if (*in == 0.0f) return 0x0000;
-    if(_isnan(*in)) return 0x7C01;
+    if(isnan(*in)) return 0x7C01;
     if (isinf(*in)) return (*in < 0.0f ? 0xFC00 : 0x7c00);
 
     if(tmp < powf(2, 10)) {