diff --git a/msvc/ecl/config.h.msvc6 b/msvc/ecl/config.h.msvc6
index dc2d5282..906cb68e 100755
--- a/msvc/ecl/config.h.msvc6
+++ b/msvc/ecl/config.h.msvc6
@@ -201,7 +201,7 @@ typedef unsigned char ecl_base_char;
 #define ECL_SLOTS_LIMIT	32768
 
 /* compiler understands long double                                     */
-/* #undef ECL_LONG_FLOAT */
+#define ECL_LONG_FLOAT
 /* compiler understands complex                                         */
 /* #undef HAVE_DOUBLE_COMPLEX */
 /* #undef HAVE_FLOAT_COMPLEX */