diff --git a/fmt/format.cc b/fmt/format.cc
index d63c5543..ef429d12 100644
--- a/fmt/format.cc
+++ b/fmt/format.cc
@@ -41,7 +41,7 @@
 #endif
 
 #if FMT_USE_WINDOWS_H
-# ifndef WIN32_LEAN_AND_MEAN
+# if !defined(FMT_HEADER_ONLY) && !defined(WIN32_LEAN_AND_MEAN)
 #  define WIN32_LEAN_AND_MEAN
 # endif
 # if defined(NOMINMAX) || defined(FMT_WIN_MINMAX)