diff --git a/src/win_delay_load_hook.c b/src/win_delay_load_hook.c
index f397cfa195..b1e170aa13 100644
--- a/src/win_delay_load_hook.c
+++ b/src/win_delay_load_hook.c
@@ -9,7 +9,10 @@
 
 #ifdef _MSC_VER
 
+#ifndef WIN32_LEAN_AND_MEAN
 #define WIN32_LEAN_AND_MEAN
+#endif
+
 #include <windows.h>
 
 #include <delayimp.h>