diff --git a/ftplugin/python/coveragepy.vim b/ftplugin/python/coveragepy.vim
index 250a29c..0c9ca5e 100755
--- a/ftplugin/python/coveragepy.vim
+++ b/ftplugin/python/coveragepy.vim
@@ -84,14 +84,17 @@ endfunction
 
 
 function! s:ClearSigns() abort
-    let placements = split(execute('sign place file=' . bufname('%')), '\n')
-    let fname = bufname('%')
+    let buf = bufnr('%')
+    let placements = split(execute('sign place buffer='.buf), '\n')
     for s in placements
       let cols = split(s)
+      let id = split(cols[1], '=')[-1]
+      if id !=# s:sign_id
+        continue
+      endif
       let name = split(cols[-1], '=')[-1]
-      if name[0:8] ==# 'uncovered'
-        let id = s:sign_id
-        exe printf('sign unplace %d file=%s', id, fname)
+      if name[-9:] ==# 'uncovered'
+        exe printf('sign unplace %d buffer=%d', s:sign_id, buf)
       endif
     endfor
 endfunction