diff --git a/msvc/ecl/config.h.msvc6 b/msvc/ecl/config.h.msvc6
index 64a1ea5a7..c2f387e35 100755
--- a/msvc/ecl/config.h.msvc6
+++ b/msvc/ecl/config.h.msvc6
@@ -13,6 +13,8 @@
     See file '../Copyright' for full details.
 */
 
+#define ECL_MS_WINDOWS_HOST
+
 /*
  * If ECL_API has been predefined, that means we are building the core
  * library and, under windows, we must tell the compiler to export