diff --git a/src/span.h b/src/span.h
index df4d906d8..77a578ab9 100644
--- a/src/span.h
+++ b/src/span.h
@@ -1,94 +1,106 @@
 // Copyright (c) 2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_SPAN_H
 #define BITCOIN_SPAN_H
 
 #include <algorithm>
+#include <cassert>
 #include <cstddef>
 #include <type_traits>
 
 /** A Span is an object that can refer to a contiguous sequence of objects.
  *
  * It implements a subset of C++20's std::span.
  */
 template <typename C> class Span {
     C *m_data;
     std::ptrdiff_t m_size;
 
 public:
     constexpr Span() noexcept : m_data(nullptr), m_size(0) {}
     constexpr Span(C *data, std::ptrdiff_t size) noexcept
         : m_data(data), m_size(size) {}
     constexpr Span(C *data, C *end) noexcept
         : m_data(data), m_size(end - data) {}
 
     constexpr C *data() const noexcept { return m_data; }
     constexpr C *begin() const noexcept { return m_data; }
     constexpr C *end() const noexcept { return m_data + m_size; }
+    constexpr C &front() const noexcept { return m_data[0]; }
+    constexpr C &back() const noexcept { return m_data[m_size - 1]; }
     constexpr std::ptrdiff_t size() const noexcept { return m_size; }
     constexpr C &operator[](std::ptrdiff_t pos) const noexcept {
         return m_data[pos];
     }
 
     constexpr Span<C> subspan(std::ptrdiff_t offset) const noexcept {
         return Span<C>(m_data + offset, m_size - offset);
     }
     constexpr Span<C> subspan(std::ptrdiff_t offset, std::ptrdiff_t count) const
         noexcept {
         return Span<C>(m_data + offset, count);
     }
     constexpr Span<C> first(std::ptrdiff_t count) const noexcept {
         return Span<C>(m_data, count);
     }
     constexpr Span<C> last(std::ptrdiff_t count) const noexcept {
         return Span<C>(m_data + m_size - count, count);
     }
 
     friend constexpr bool operator==(const Span &a, const Span &b) noexcept {
         return a.size() == b.size() &&
                std::equal(a.begin(), a.end(), b.begin());
     }
     friend constexpr bool operator!=(const Span &a, const Span &b) noexcept {
         return !(a == b);
     }
     friend constexpr bool operator<(const Span &a, const Span &b) noexcept {
         return std::lexicographical_compare(a.begin(), a.end(), b.begin(),
                                             b.end());
     }
     friend constexpr bool operator<=(const Span &a, const Span &b) noexcept {
         return !(b < a);
     }
     friend constexpr bool operator>(const Span &a, const Span &b) noexcept {
         return (b < a);
     }
     friend constexpr bool operator>=(const Span &a, const Span &b) noexcept {
         return !(a < b);
     }
 };
 
 /** Create a span to a container exposing data() and size().
  *
  * This correctly deals with constness: the returned Span's element type will be
  * whatever data() returns a pointer to. If either the passed container is
  * const, or its element type is const, the resulting span will have a const
  * element type.
  *
  * std::span will have a constructor that implements this functionality
  * directly.
  */
 template <typename A, int N> constexpr Span<A> MakeSpan(A (&a)[N]) {
     return Span<A>(a, N);
 }
 
 template <typename V>
 constexpr Span<
     typename std::remove_pointer<decltype(std::declval<V>().data())>::type>
 MakeSpan(V &v) {
     return Span<
         typename std::remove_pointer<decltype(std::declval<V>().data())>::type>(
         v.data(), v.size());
 }
 
+/** Pop the last element off a span, and return a reference to that element. */
+template <typename T> T &SpanPopBack(Span<T> &span) {
+    size_t size = span.size();
+    assert(size > 0);
+    T &back = span[size - 1];
+    span = Span<T>(span.data(), size - 1);
+    return back;
+}
+
 #endif // BITCOIN_SPAN_H