diff --git a/cmake/WindowsSupport.cmake b/cmake/WindowsSupport.cmake
index 93c1309..5a2eaa9 100644
--- a/cmake/WindowsSupport.cmake
+++ b/cmake/WindowsSupport.cmake
@@ -30,9 +30,6 @@ endif()
 
 # Win32 file I/O
 set(win32_io_default OFF)
-if(WIN32)
-    set(win32_io_default ON)
-endif()
 
 option(win32-io "Use Win32 I/O" ${win32_io_default})