diff --git a/pisi/history.py b/pisi/history.py
index f4b5bca1..fa2ca859 100644
--- a/pisi/history.py
+++ b/pisi/history.py
@@ -29,10 +29,7 @@ class PackageInfo:
     a_build = [autoxml.String, autoxml.optional]
 
     def __str__(self):
-        vrb = self.version + "-" + self.release
-        if self.build:
-            vrb += "-" + self.build
-        return vrb
+        return self.version + "-" + self.release + "-" + (self.build or '?')
 
 class Package: