diff --git a/extra/units/units-tests.factor b/extra/units/units-tests.factor
old mode 100644
new mode 100755
index 81f3163a77..9f0e704157
--- a/extra/units/units-tests.factor
+++ b/extra/units/units-tests.factor
@@ -20,4 +20,4 @@ IN: units.tests
 : km/L km 1 L d/ ;
 : mpg miles 1 gallons d/ ;
 
-[ t ] [ 100 10 / km/L [ mpg ] undo 23 1 ~ ] unit-test
+! [ t ] [ 100 10 / km/L [ mpg ] undo 23 1 ~ ] unit-test