diff --git a/scheme/completer.scm b/scheme/completer.scm
index aa89874..df61ec6 100644
--- a/scheme/completer.scm
+++ b/scheme/completer.scm
@@ -143,11 +143,13 @@
 		 (lambda (completed-line cursor-index)
 		   (list completed-line '() cursor-index to-complete parsed))))
               (else
-               (let ((common-prefix (strings-common-prefix completions)))
+               (let ((common-prefix (strings-common-prefix completions))
+                     (prefix (to-complete-prefix to-complete)))
                  (debug-message "common-prefix is" common-prefix)
-                 (if (<= (string-length common-prefix)
-                         (string-length (to-complete-prefix to-complete)))
-                     (list #f completions cursor-index to-complete parsed)
+                 (if (> (string-length common-prefix)
+                        (if prefix
+                            (string-length prefix)
+                            0))
                      (call-with-values
                          (lambda ()
                            (unparse-command-line
@@ -155,7 +157,8 @@
                                      (display common-prefix))))
                        (lambda (completed-line cursor-index)
                          (list completed-line '()
-                               cursor-index to-complete parsed))))))))))))
+                               cursor-index to-complete parsed)))
+                     (list #f completions cursor-index to-complete parsed))))))))))
 
 
 (define (strings-common-prefix strs)