diff --git a/include/fmt/format.cc b/include/fmt/format.cc
index e41f2cba..97192d85 100644
--- a/include/fmt/format.cc
+++ b/include/fmt/format.cc
@@ -22,6 +22,9 @@
 #endif
 
 #if FMT_USE_WINDOWS_H
+# if !defined(FMT_HEADER_ONLY) && !defined(WIN32_LEAN_AND_MEAN)
+#  define WIN32_LEAN_AND_MEAN
+# endif
 # if defined(NOMINMAX) || defined(FMT_WIN_MINMAX)
 #  include <windows.h>
 # else
diff --git a/include/fmt/posix.cc b/include/fmt/posix.cc
index a3c076ca..a7a255ac 100644
--- a/include/fmt/posix.cc
+++ b/include/fmt/posix.cc
@@ -19,6 +19,9 @@
 #ifndef _WIN32
 # include <unistd.h>
 #else
+# ifndef WIN32_LEAN_AND_MEAN
+#  define WIN32_LEAN_AND_MEAN
+# endif
 # include <windows.h>
 # include <io.h>