diff --git a/src/plugins/bearer/generic/qgenericengine.cpp b/src/plugins/bearer/generic/qgenericengine.cpp
index 02ea7abf88..059617b367 100644
--- a/src/plugins/bearer/generic/qgenericengine.cpp
+++ b/src/plugins/bearer/generic/qgenericengine.cpp
@@ -37,6 +37,9 @@
 **
 ****************************************************************************/
 
+// see comment in ../platformdefs_win.h.
+#define WIN32_LEAN_AND_MEAN 1
+
 #include "qgenericengine.h"
 #include "../qnetworksession_impl.h"
 
diff --git a/src/plugins/bearer/platformdefs_win.h b/src/plugins/bearer/platformdefs_win.h
index 8fb2f1bcc5..5a8487d868 100644
--- a/src/plugins/bearer/platformdefs_win.h
+++ b/src/plugins/bearer/platformdefs_win.h
@@ -40,6 +40,8 @@
 #ifndef QPLATFORMDEFS_WIN_H
 #define QPLATFORMDEFS_WIN_H
 
+// Since we need to include winsock2.h, we need to define WIN32_LEAN_AND_MEAN
+// somewhere above so windows.h won't include winsock.h.
 #include <winsock2.h>
 #include <mswsock.h>
 #undef interface
diff --git a/src/plugins/bearer/qnetworksession_impl.cpp b/src/plugins/bearer/qnetworksession_impl.cpp
index 5ce51670f7..7756709e55 100644
--- a/src/plugins/bearer/qnetworksession_impl.cpp
+++ b/src/plugins/bearer/qnetworksession_impl.cpp
@@ -37,6 +37,9 @@
 **
 ****************************************************************************/
 
+// see comment in ../platformdefs_win.h.
+#define WIN32_LEAN_AND_MEAN 1
+
 #include "qnetworksession_impl.h"
 #include "qbearerengine_impl.h"