diff --git a/src/coins.h b/src/coins.h
--- a/src/coins.h
+++ b/src/coins.h
@@ -16,7 +16,7 @@
 #include <cassert>
 #include <cstdint>
 
-#include <boost/unordered_map.hpp>
+#include <unordered_map>
 
 /**
  * A UTXO entry.
@@ -296,6 +296,9 @@
      * This *must* return size_t. With Boost 1.46 on 32-bit systems the
      * unordered_map will behave unpredictably if the custom hasher returns a
      * uint64_t, resulting in failures when syncing the chain (#4634).
+     * Note: This information above might be outdated as the unordered map
+     * container type has meanwhile been switched to the C++ standard library
+     * implementation.
      */
     size_t operator()(const uint256 &txid) const {
         return SipHashUint256(k0, k1, txid);
@@ -321,7 +324,7 @@
     CCoinsCacheEntry() : coins(), flags(0) {}
 };
 
-typedef boost::unordered_map<uint256, CCoinsCacheEntry, SaltedTxidHasher>
+typedef std::unordered_map<uint256, CCoinsCacheEntry, SaltedTxidHasher>
     CCoinsMap;
 
 /** Cursor for iterating over CoinsView state */
diff --git a/src/memusage.h b/src/memusage.h
--- a/src/memusage.h
+++ b/src/memusage.h
@@ -13,8 +13,8 @@
 #include <set>
 #include <vector>
 
-#include <boost/unordered_map.hpp>
-#include <boost/unordered_set.hpp>
+#include <unordered_map>
+#include <unordered_set>
 
 namespace memusage {
 
@@ -161,20 +161,20 @@
 
 // Boost data structures
 
-template <typename X> struct boost_unordered_node : private X {
+template <typename X> struct unordered_node : private X {
 private:
     void *ptr;
 };
 
 template <typename X, typename Y>
-static inline size_t DynamicUsage(const boost::unordered_set<X, Y> &s) {
-    return MallocUsage(sizeof(boost_unordered_node<X>)) * s.size() +
+static inline size_t DynamicUsage(const std::unordered_set<X, Y> &s) {
+    return MallocUsage(sizeof(unordered_node<X>)) * s.size() +
            MallocUsage(sizeof(void *) * s.bucket_count());
 }
 
 template <typename X, typename Y, typename Z>
-static inline size_t DynamicUsage(const boost::unordered_map<X, Y, Z> &m) {
-    return MallocUsage(sizeof(boost_unordered_node<std::pair<const X, Y>>)) *
+static inline size_t DynamicUsage(const std::unordered_map<X, Y, Z> &m) {
+    return MallocUsage(sizeof(unordered_node<std::pair<const X, Y>>)) *
                m.size() +
            MallocUsage(sizeof(void *) * m.bucket_count());
 }
diff --git a/src/validation.h b/src/validation.h
--- a/src/validation.h
+++ b/src/validation.h
@@ -31,7 +31,7 @@
 #include <atomic>
 
 #include <boost/filesystem/path.hpp>
-#include <boost/unordered_map.hpp>
+#include <unordered_map>
 
 class CBlockIndex;
 class CBlockTreeDB;
@@ -174,7 +174,7 @@
 extern CScript COINBASE_FLAGS;
 extern CCriticalSection cs_main;
 extern CTxMemPool mempool;
-typedef boost::unordered_map<uint256, CBlockIndex *, BlockHasher> BlockMap;
+typedef std::unordered_map<uint256, CBlockIndex *, BlockHasher> BlockMap;
 extern BlockMap mapBlockIndex;
 extern uint64_t nLastBlockTx;
 extern uint64_t nLastBlockSize;