diff --git a/speculation-rules.bs b/speculation-rules.bs
index ccb3c96..6bcf76c 100644
--- a/speculation-rules.bs
+++ b/speculation-rules.bs
@@ -477,7 +477,6 @@ add the following step
     1. Let |patterns| be an empty [=list=].
     1. [=list/For each=] |rawPattern| of |rawPatterns|:
       1. Let |pattern| be the result of [=building a URL pattern from an Infra value=] |rawPattern| given |baseURL|. If this step throws, catch the exception and return null.
-      1. [=Assert=]: |pattern| is a [=URL pattern=].
       1. [=list/Append=] |pattern| to |patterns|.
     1. Return a [=document rule URL pattern predicate=] whose [=document rule URL pattern predicate/patterns=] is |patterns|.
   1. If |predicateType| is "`selector_matches`":