diff --git a/src/acl/ExtUser.h b/src/acl/ExtUser.h
index 3faaeeb0f06..a851be8824f 100644
--- a/src/acl/ExtUser.h
+++ b/src/acl/ExtUser.h
@@ -27,6 +27,7 @@ class ACLExtUser : public Acl::Node
     char const *typeString() const override;
     void parse() override;
     int match(ACLChecklist *checklist) override;
+    bool requiresRequest() const override { return true; }
     SBufList dump() const override;
     bool empty () const override;
 
diff --git a/src/acl/SourceDomain.cc b/src/acl/SourceDomain.cc
index f3267f15bba..343e0d7ae15 100644
--- a/src/acl/SourceDomain.cc
+++ b/src/acl/SourceDomain.cc
@@ -30,7 +30,11 @@ LookupDone(const char *, const Dns::LookupDetails &details, void *data)
 {
     ACLFilledChecklist *checklist = Filled((ACLChecklist*)data);
     checklist->markSourceDomainChecked();
-    checklist->request->recordLookup(details);
+    if (checklist->request)
+        checklist->request->recordLookup(details);
+    else
+        debugs(28, 3, "no request to recordLookup()");
+
     checklist->resumeNonBlockingCheck();
 }