1 files changed, 3 insertions, 0 deletions
diff --git a/win/tcl.m4 b/win/tcl.m4
index 0f79dae..ae909bb 100644
--- a/win/tcl.m4
+++ b/win/tcl.m4
@@ -253,6 +253,9 @@ AC_DEFUN(SC_ENABLE_THREADS, [
 	AC_MSG_RESULT(yes)
 	TCL_THREADS=1
 	AC_DEFINE(TCL_THREADS)
+	# USE_THREAD_ALLOC tells us to try the special thread-based
+	# allocator that significantly reduces lock contention
+	AC_DEFINE(USE_THREAD_ALLOC)
     else
 	TCL_THREADS=0
 	AC_MSG_RESULT([no (default)])