diff --git a/msvc/ecl/config.h.msvc6 b/msvc/ecl/config.h.msvc6
index f46ddb633..b34ffcec8 100644
--- a/msvc/ecl/config.h.msvc6
+++ b/msvc/ecl/config.h.msvc6
@@ -61,6 +61,8 @@
 #define ECL_THREADS @ECL_THREADS@
 #if ECL_THREADS
 # define GC_WIN32_THREADS
+# define GC_THREADS
+# define ECL_WINDOWS_THREADS
 #else
 # undef ECL_THREADS
 #endif
diff --git a/src/h/config.h.in b/src/h/config.h.in
index f4dc83ecd..70e7f42d8 100644
--- a/src/h/config.h.in
+++ b/src/h/config.h.in
@@ -74,10 +74,12 @@
 #undef GBC_BOEHM
 #ifdef GBC_BOEHM
 # ifdef ECL_WINDOWS_THREADS
-#   define GC_WIN32_THREADS
+#   define GC_WIN32_THREADS	/* For older versions */
+#   define GC_THREADS		/* For >= 7.2 */
 # else
 #  ifdef ECL_THREADS
-#    define GC_PTHREADS
+#    define GC_PTHREADS		/* For older versions */
+#    define GC_THREADS		/* For >= 7.2 */
 #  endif
 # endif
 # define ECL_DYNAMIC_VV