diff --git a/members-base.scm b/members-base.scm
index 501211f..ec74ab3 100644
--- a/members-base.scm
+++ b/members-base.scm
@@ -364,7 +364,14 @@
        (print "      Invalid: "
 	      (length iids)
 	      " ("
-	      (string-intersperse (map number->string iids) ", ")
+	      (string-intersperse
+	       (map (lambda (id)
+		      (let ((mr (find-member-by-id MB id)))
+			(member-format
+			 "~I - ~N"
+			 mr)))
+		    iids)
+	       ", ")
 	      ")"))))
 
  ;; Performs self-tests of this module.