diff --git a/spec.html b/spec.html
index 70960724b9..67ef5e5de0 100644
--- a/spec.html
+++ b/spec.html
@@ -6646,6 +6646,7 @@ <h1>
         1. If _obj_ is a Proxy exotic object, then
           1. Perform ? ValidateNonRevokedProxy(_obj_).
           1. Let _proxyTarget_ be _obj_.[[ProxyTarget]].
+          1. Assert: _proxyTarget_ is a function object.
           1. Return ? GetFunctionRealm(_proxyTarget_).
         1. [id="step-getfunctionrealm-default-return"] Return the current Realm Record.
       </emu-alg>