diff --git a/src/mezz/mezz-secure.r b/src/mezz/mezz-secure.r
index ac7f3303cc..fd6212a6ff 100644
--- a/src/mezz/mezz-secure.r
+++ b/src/mezz/mezz-secure.r
@@ -82,7 +82,9 @@ secure: function/with [
 
 	; Set each policy target separately:
 	foreach [target pol] policy [
-		assert/type [target [word! file! url!] pol [block! word! integer!]]
+		try/except [
+			assert/type [target [word! file! url!] pol [block! word! integer!]]
+		][	cause-error 'access 'security-error reduce [target pol] ]
 		set-policy target make-policy target pol pol-obj
 	]