Add WIN32_LEAN_AND_MEAN for windows.h include.
diff --git a/zconf.h b/zconf.h
index 5e1d68a..0ba5bd5 100644
--- a/zconf.h
+++ b/zconf.h
@@ -349,6 +349,9 @@
 #    ifdef FAR
 #      undef FAR
 #    endif
+#    ifndef WIN32_LEAN_AND_MEAN
+#      define WIN32_LEAN_AND_MEAN
+#    endif
 #    include <windows.h>
      /* No need for _export, use ZLIB.DEF instead. */
      /* For complete Windows compatibility, use WINAPI, not __stdcall. */
diff --git a/zconf.h.cmakein b/zconf.h.cmakein
index a7f24cc..62c5261 100644
--- a/zconf.h.cmakein
+++ b/zconf.h.cmakein
@@ -351,6 +351,9 @@
 #    ifdef FAR
 #      undef FAR
 #    endif
+#    ifndef WIN32_LEAN_AND_MEAN
+#      define WIN32_LEAN_AND_MEAN
+#    endif
 #    include <windows.h>
      /* No need for _export, use ZLIB.DEF instead. */
      /* For complete Windows compatibility, use WINAPI, not __stdcall. */
diff --git a/zconf.h.in b/zconf.h.in
index 5e1d68a..0ba5bd5 100644
--- a/zconf.h.in
+++ b/zconf.h.in
@@ -349,6 +349,9 @@
 #    ifdef FAR
 #      undef FAR
 #    endif
+#    ifndef WIN32_LEAN_AND_MEAN
+#      define WIN32_LEAN_AND_MEAN
+#    endif
 #    include <windows.h>
      /* No need for _export, use ZLIB.DEF instead. */
      /* For complete Windows compatibility, use WINAPI, not __stdcall. */