diff --git a/configuration.scm b/configuration.scm
index b4eb765..26abdba 100644
--- a/configuration.scm
+++ b/configuration.scm
@@ -56,6 +56,8 @@
  ;;  'quiet - ignore
  (define *member-file-check-syntax* (make-parameter 'error))
 
+ ;; Default as specified by the original implementation if the 'joined
+ ;; key is missing in member file.
  (define *member-default-joined* (make-parameter (make-month 2015 1)))
 
  )
diff --git a/period.scm b/period.scm
index 7d5257b..a710b76 100644
--- a/period.scm
+++ b/period.scm
@@ -78,7 +78,10 @@
 		   (loop (cdr l)
 			 ps
 			 (cdr m)))
-	       (error 'period-markers->periods "Invalid start/stop sequence marker" m))))))
+	       (if (eq? (*member-file-check-syntax*) 'error)
+		   (error 'period-markers->periods "Invalid start/stop sequence marker" m)
+		   (reverse ps) ; Just ignore it for now
+		   ))))))
 
  ;; Returns duration of period in months. Start is included, end is
  ;; not. The period contains the month just before the specified end.