diff --git a/scheme/completer.scm b/scheme/completer.scm
index bb0c05d..aa89874 100644
--- a/scheme/completer.scm
+++ b/scheme/completer.scm
@@ -145,7 +145,8 @@
               (else
                (let ((common-prefix (strings-common-prefix completions)))
                  (debug-message "common-prefix is" common-prefix)
-                 (if (string=? common-prefix "")
+                 (if (<= (string-length common-prefix)
+                         (string-length (to-complete-prefix to-complete)))
                      (list #f completions cursor-index to-complete parsed)
                      (call-with-values
                          (lambda ()
@@ -153,7 +154,8 @@
                             parsed (lambda (to-complete)
                                      (display common-prefix))))
                        (lambda (completed-line cursor-index)
-                         (list completed-line completions cursor-index to-complete parsed))))))))))))
+                         (list completed-line '()
+                               cursor-index to-complete parsed))))))))))))
 
 
 (define (strings-common-prefix strs)