diff --git a/tests/test_helper.tcl b/tests/test_helper.tcl
index b2e58b44c..701bbf3d6 100644
--- a/tests/test_helper.tcl
+++ b/tests/test_helper.tcl
@@ -2,6 +2,8 @@
 # This softare is released under the BSD License. See the COPYING file for
 # more information.
 
+package require Tcl 8.5
+
 set tcl_precision 17
 source tests/support/redis.tcl
 source tests/support/server.tcl