diff --git a/daemon/table/name-tree-hashtable.cpp b/daemon/table/name-tree-hashtable.cpp
index 421f298..e6b3c33 100644
--- a/daemon/table/name-tree-hashtable.cpp
+++ b/daemon/table/name-tree-hashtable.cpp
@@ -57,12 +57,12 @@
 using HashFunc = std::conditional<(sizeof(HashValue) > 4), Hash64, Hash32>::type;
 
 HashValue
-computeHash(const Name& name, ssize_t prefixLen)
+computeHash(const Name& name, size_t prefixLen)
 {
   name.wireEncode(); // ensure wire buffer exists
 
   HashValue h = 0;
-  for (size_t i = 0, last = prefixLen < 0 ? name.size() : prefixLen; i < last; ++i) {
+  for (size_t i = 0, last = std::min(prefixLen, name.size()); i < last; ++i) {
     const name::Component& comp = name[i];
     h ^= HashFunc::compute(comp.wire(), comp.size());
   }
@@ -70,11 +70,11 @@
 }
 
 HashSequence
-computeHashes(const Name& name, ssize_t prefixLen)
+computeHashes(const Name& name, size_t prefixLen)
 {
   name.wireEncode(); // ensure wire buffer exists
 
-  size_t last = prefixLen < 0 ? name.size() : std::min(static_cast<size_t>(prefixLen), name.size());
+  size_t last = std::min(prefixLen, name.size());
   HashSequence seq;
   seq.reserve(last + 1);
 
diff --git a/daemon/table/name-tree-hashtable.hpp b/daemon/table/name-tree-hashtable.hpp
index d7ca6a6..ec5caa0 100644
--- a/daemon/table/name-tree-hashtable.hpp
+++ b/daemon/table/name-tree-hashtable.hpp
@@ -42,22 +42,16 @@
  */
 using HashSequence = std::vector<HashValue>;
 
-/** \brief computes a single hash value
- *  \param name base name
- *  \param prefixLen if non-negative, compute hash value for name.getPrefix(prefixLen);
- *                   if negative, compute hash value for complete name
+/** \brief computes hash value of \p name.getPrefix(prefixLen)
  */
 HashValue
-computeHash(const Name& name, ssize_t prefixLen = -1);
+computeHash(const Name& name, size_t prefixLen = std::numeric_limits<size_t>::max());
 
-/** \brief computes hash values for each prefix of name
- *  \param name base name
- *  \param prefixLen if non-negative, compute up to the first \p prefixLen name components;
- *                   if negative, compute all hash values
+/** \brief computes hash values for each prefix of \p name.getPrefix(prefixLen)
  *  \return a hash sequence, where the i-th hash value equals computeHash(name, i)
  */
 HashSequence
-computeHashes(const Name& name, ssize_t prefixLen = -1);
+computeHashes(const Name& name, size_t prefixLen = std::numeric_limits<size_t>::max());
 
 /** \brief a hashtable node
  *
diff --git a/daemon/table/name-tree.cpp b/daemon/table/name-tree.cpp
index 65cafd7..1fa54af 100644
--- a/daemon/table/name-tree.cpp
+++ b/daemon/table/name-tree.cpp
@@ -44,7 +44,7 @@
 NameTree::lookup(const Name& name, bool enforceMaxDepth)
 {
   NFD_LOG_TRACE("lookup " << name);
-  size_t depth = enforceMaxDepth ? getMaxDepth() : name.size();
+  size_t depth = enforceMaxDepth ? std::min(name.size(), getMaxDepth()) : name.size();
 
   HashSequence hashes = computeHashes(name, depth);
   const Node* node = nullptr;
@@ -146,9 +146,9 @@
 }
 
 Entry*
-NameTree::findExactMatch(const Name& name) const
+NameTree::findExactMatch(const Name& name, size_t prefixLen) const
 {
-  const Node* node = m_ht.find(name, name.size());
+  const Node* node = m_ht.find(name, std::min(name.size(), prefixLen));
   return node == nullptr ? nullptr : &node->entry;
 }
 
@@ -186,13 +186,13 @@
   const Entry* nte = this->getEntry(pitEntry);
   BOOST_ASSERT(nte != nullptr);
 
+  // PIT entry Interest name either exceeds depth limit or ends with an implicit digest: go deeper
   if (nte->getName().size() < pitEntry.getName().size()) {
-    // special case: PIT entry whose Interest name ends with an implicit digest
-    // are attached to the name tree entry with one-shorter-prefix.
-    BOOST_ASSERT(pitEntry.getName().at(-1).isImplicitSha256Digest());
-    BOOST_ASSERT(nte->getName() == pitEntry.getName().getPrefix(-1));
-    const Entry* exact = this->findExactMatch(pitEntry.getName());
-    if (exact != nullptr) {
+    for (size_t prefixLen = nte->getName().size() + 1; prefixLen <= pitEntry.getName().size(); ++prefixLen) {
+      const Entry* exact = this->findExactMatch(pitEntry.getName(), prefixLen);
+      if (exact == nullptr) {
+        break;
+      }
       nte = exact;
     }
   }
diff --git a/daemon/table/name-tree.hpp b/daemon/table/name-tree.hpp
index 6d04821..04e504e 100644
--- a/daemon/table/name-tree.hpp
+++ b/daemon/table/name-tree.hpp
@@ -136,10 +136,10 @@
 
 public: // matching
   /** \brief exact match lookup
-   *  \return entry with \p name, or nullptr if it does not exist
+   *  \return entry with \p name.getPrefix(prefixLen), or nullptr if it does not exist
    */
   Entry*
-  findExactMatch(const Name& name) const;
+  findExactMatch(const Name& name, size_t prefixLen = std::numeric_limits<size_t>::max()) const;
 
   /** \brief longest prefix matching
    *  \return entry whose name is a prefix of \p name and passes \p entrySelector,
diff --git a/daemon/table/pit.cpp b/daemon/table/pit.cpp
index 3256b89..2050417 100644
--- a/daemon/table/pit.cpp
+++ b/daemon/table/pit.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2014-2016,  Regents of the University of California,
+/*
+ * Copyright (c) 2014-2017,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -51,7 +51,7 @@
   // ensure NameTree entry exists
   name_tree::Entry* nte = nullptr;
   if (allowInsert) {
-    nte = &m_nameTree.lookup(nteName);
+    nte = &m_nameTree.lookup(nteName, true);
   }
   else {
     nte = m_nameTree.findExactMatch(nteName);
@@ -61,7 +61,7 @@
   }
 
   // check if PIT entry already exists
-  size_t nteNameLen = nteName.size();
+  size_t nteNameLen = nte->getName().size();
   const std::vector<shared_ptr<Entry>>& pitEntries = nte->getPitEntries();
   auto it = std::find_if(pitEntries.begin(), pitEntries.end(),
     [&interest, nteNameLen] (const shared_ptr<Entry>& entry) {