diff --git a/test/unit_test/test_units.cpp b/test/unit_test/test_units.cpp
index ff9f7e18..feeca36a 100644
--- a/test/unit_test/test_units.cpp
+++ b/test/unit_test/test_units.cpp
@@ -69,7 +69,7 @@ namespace {
   static_assert(1ft == 12in);
   static_assert(1mi == 1760yd);
 
-//  static_assert(5in + 8cm == 207mm);
+  static_assert(5in + 8cm == 207mm);