diff --git a/src/cpp/ripple/ripple_LedgerEntrySet.cpp b/src/cpp/ripple/ripple_LedgerEntrySet.cpp
index 27b100a7b5..3a82c11825 100644
--- a/src/cpp/ripple/ripple_LedgerEntrySet.cpp
+++ b/src/cpp/ripple/ripple_LedgerEntrySet.cpp
@@ -944,6 +944,9 @@ bool LedgerEntrySet::dirNext (
     STVector256             svIndexes   = sleNode->getFieldV256 (sfIndexes);
     std::vector<uint256>&   vuiIndexes  = svIndexes.peekValue ();
 
+
+    assert (uDirEntry <= vuiIndexes.size());
+
     if (uDirEntry >= vuiIndexes.size ())
     {
         uint64              uNodeNext   = sleNode->getFieldU64 (sfIndexNext);