diff --git a/masstree_iterator.hh b/masstree_iterator.hh
index 4b60208..3f1cb8e 100644
--- a/masstree_iterator.hh
+++ b/masstree_iterator.hh
@@ -50,6 +50,10 @@ class basic_table<P>::iterator
         ikey_type x[(MASSTREE_MAXKEYLEN + sizeof(ikey_type) - 1)/sizeof(ikey_type)];
         char s[MASSTREE_MAXKEYLEN];
     } keybuf_;
+    union {
+        ikey_type x[(MASSTREE_MAXKEYLEN + sizeof(ikey_type) - 1)/sizeof(ikey_type)];
+        char s[MASSTREE_MAXKEYLEN];
+    } keybuf2_;
 
     void advance(bool emit_equal = false);
 
@@ -98,7 +102,10 @@ basic_table<P>::iterator::advance(bool emit_equal) {
     Str suffix;
     char suffixbuf[MASSTREE_MAXKEYLEN];
 
+    memcpy(keybuf2_.s, keybuf_.s, sizeof(keybuf_));
+
  retry_root:
+    memcpy(keybuf_.s, keybuf2_.s, sizeof(keybuf2_));
     ka_.unshift_all();
     root = table_->root();
     n = root->reach_leaf(ka_, v, *ti_);