diff --git a/fftools/cmdutils.c b/fftools/cmdutils.c
index 9cfbc45..e3447e6 100644
--- a/fftools/cmdutils.c
+++ b/fftools/cmdutils.c
@@ -63,6 +63,8 @@
 #include <sys/resource.h>
 #endif
 #ifdef _WIN32
+#define _WIN32_WINNT 0x0502
+#define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 #endif
 
diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 01f0410..dbb0736 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -23,6 +23,10 @@
  * multimedia converter based on the FFmpeg libraries
  */
 
+#define _WIN32_WINNT 0x0502	// Must be less than 0x0600, because otherwise WinSock2.h defines "pollfd" which then gets redefined in "os_support.h".
+#define WIN32_LEAN_AND_MEAN
+
+
 #include "config.h"
 #include <ctype.h>
 #include <string.h>