diff --git a/pisi/package.py b/pisi/package.py
index 0f5089ad..af413ffd 100644
--- a/pisi/package.py
+++ b/pisi/package.py
@@ -47,8 +47,12 @@ class Package:
         dest = ctx.config.packages_dir()
         self.filepath = join(dest, url.filename())
 
-        #FIXME: also check sha1sum
-        if not exists(self.filepath):
+        sha1sum = None
+        if exists(self.filepath):
+            sha1sum = util.sha1_file(self.filepath)
+
+        name, version = util.parse_package_name(basename(self.filepath))
+        if sha1sum != ctx.packagedb.get_package(name).packageHash:
             try:
                 fetch_url(url, dest, ctx.ui.Progress)
             except pisi.fetcher.FetchError: