diff --git a/caching/superblock.cc b/caching/superblock.cc
index 0d550e8..3eb7231 100644
--- a/caching/superblock.cc
+++ b/caching/superblock.cc
@@ -61,6 +61,7 @@ namespace {
 //----------------------------------------------------------------
 
 superblock_flags::superblock_flags()
+	: unhandled_flags_(0)
 {
 }