diff --git a/src/detail/pending-interest.hpp b/src/detail/pending-interest.hpp
index 791f59b..0a66dca 100644
--- a/src/detail/pending-interest.hpp
+++ b/src/detail/pending-interest.hpp
@@ -57,13 +57,13 @@
   }
 
   const shared_ptr<const Interest>&
-  getInterest()
+  getInterest() const
   {
     return m_interest;
   }
 
   const OnData&
-  getOnData()
+  getOnData() const
   {
     return m_onData;
   }
@@ -73,7 +73,7 @@
    * @return true if this interest timed out, otherwise false.
    */
   bool
-  isTimedOut(const time::steady_clock::TimePoint& now)
+  isTimedOut(const time::steady_clock::TimePoint& now) const
   {
     return now >= m_timeout;
   }
@@ -82,7 +82,7 @@
    * Call m_onTimeout (if defined).  This ignores exceptions from the m_onTimeout.
    */
   void
-  callTimeout()
+  callTimeout() const
   {
     if (m_onTimeout) {
       m_onTimeout(*m_interest);
@@ -114,7 +114,8 @@
   bool
   operator()(const shared_ptr<const PendingInterest>& pendingInterest) const
   {
-    return (reinterpret_cast<const PendingInterestId*>(pendingInterest.get()) == m_id);
+    return (reinterpret_cast<const PendingInterestId*>(
+              pendingInterest->getInterest().get()) == m_id);
   }
 private:
   const PendingInterestId* m_id;
diff --git a/src/face.cpp b/src/face.cpp
index 79d8dc1..42fc522 100644
--- a/src/face.cpp
+++ b/src/face.cpp
@@ -193,6 +193,12 @@
   m_ioService->post(bind(&Impl::asyncRemovePendingInterest, m_impl, pendingInterestId));
 }
 
+size_t
+Face::getNPendingInterests() const
+{
+  return m_impl->m_pendingInterestTable.size();
+}
+
 const RegisteredPrefixId*
 Face::setInterestFilter(const InterestFilter& interestFilter,
                         const OnInterest& onInterest,
diff --git a/src/face.hpp b/src/face.hpp
index 974aa69..3407d92 100644
--- a/src/face.hpp
+++ b/src/face.hpp
@@ -225,6 +225,12 @@
   removePendingInterest(const PendingInterestId* pendingInterestId);
 
   /**
+   * @brief Get number of pending Interests
+   */
+  size_t
+  getNPendingInterests() const;
+
+  /**
    * @brief Set InterestFilter to dispatch incoming matching interest to onInterest
    * callback and register the filtered prefix with the connected NDN forwarder
    *