diff --git a/spec/index.html b/spec/index.html
index a764b3c..4d854a8 100644
--- a/spec/index.html
+++ b/spec/index.html
@@ -145,10 +145,11 @@ <h1>Set.prototype.isSubsetOf ( _other_ )</h1>
     1. Repeat, while _index_ &lt; _thisSize_,
       1. Let _e_ be _O_.[[SetData]][_index_].
       1. Set _index_ to _index_ + 1.
-      1. Let _inOther_ be ToBoolean(? Call(_otherRec_.[[Has]], _otherRec_.[[Set]], « _e_ »)).
-      1. If _inOther_ is *false*, return *false*.
-      1. NOTE: The number of elements in _O_.[[SetData]] may have increased during execution of _otherRec_.[[Has]].
-      1. Set _thisSize_ to the number of elements of _O_.[[SetData]].
+      1. If _e_ is not ~empty~, then
+        1. Let _inOther_ be ToBoolean(? Call(_otherRec_.[[Has]], _otherRec_.[[Set]], « _e_ »)).
+        1. If _inOther_ is *false*, return *false*.
+        1. NOTE: The number of elements in _O_.[[SetData]] may have increased during execution of _otherRec_.[[Has]].
+        1. Set _thisSize_ to the number of elements of _O_.[[SetData]].
     1. Return *true*.
   </emu-alg>
 </emu-clause>