diff --git a/include/bitcoin/system/chain/input.hpp b/include/bitcoin/system/chain/input.hpp
index 1afac27da1..00fb41cdca 100644
--- a/include/bitcoin/system/chain/input.hpp
+++ b/include/bitcoin/system/chain/input.hpp
@@ -118,14 +118,15 @@ class BC_API input
     /// Requires metadata.height and median_time_past (otherwise returns true).
     bool is_locked(size_t height, uint32_t median_time_past) const NOEXCEPT;
 
-    /// Any non-zero relative locktime value locks internally-spent input.
-    bool is_internally_locked() const NOEXCEPT;
-
 protected:
     input(const chain::point::cptr& point, const chain::script::cptr& script,
         const chain::witness::cptr& witness, uint32_t sequence,
         bool valid) NOEXCEPT;
 
+    /// Any non-zero relative locktime value locks internally-spent input.
+    friend class transaction;
+    bool is_internal_lock() const NOEXCEPT;
+
 private:
     typedef struct { size_t nominal; size_t witnessed; } sizes;
 
diff --git a/include/bitcoin/system/chain/transaction.hpp b/include/bitcoin/system/chain/transaction.hpp
index 54d931a71f..5e129fb677 100644
--- a/include/bitcoin/system/chain/transaction.hpp
+++ b/include/bitcoin/system/chain/transaction.hpp
@@ -128,6 +128,9 @@ class BC_API transaction
     bool is_empty() const NOEXCEPT;
     bool is_dusty(uint64_t minimum_output_value) const NOEXCEPT;
 
+    /// Requires no metadata, true if spend in own block would be locked.
+    bool is_internal_lock(const input& in) const NOEXCEPT;
+
     /// Assumes coinbase if prevout not populated (returns only legacy sigops).
     size_t signature_operations(bool bip16, bool bip141) const NOEXCEPT;
 
diff --git a/src/chain/block.cpp b/src/chain/block.cpp
index 963c74d1c6..6806edfe1d 100644
--- a/src/chain/block.cpp
+++ b/src/chain/block.cpp
@@ -730,7 +730,7 @@ bool block::populate(const chain::context& ctx) const NOEXCEPT
             if (point != points.end())
             {
                 in->prevout = point->second;
-                in->metadata.locked = bip68 && in->is_internally_locked();
+                in->metadata.locked = bip68 && (*tx)->is_internal_lock(*in);
                 locked |= in->metadata.locked;
             }
         }
diff --git a/src/chain/input.cpp b/src/chain/input.cpp
index 6d77ee2948..71111c83c2 100644
--- a/src/chain/input.cpp
+++ b/src/chain/input.cpp
@@ -416,10 +416,11 @@ bool input::is_locked(size_t height, uint32_t median_time_past) const NOEXCEPT
         metadata.median_time_past);
 }
 
-bool input::is_internally_locked() const NOEXCEPT
+// protected (tx friend)
+bool input::is_internal_lock() const NOEXCEPT
 {
-    // Internal spends have zero relative height/mtp.
-    return is_locked(sequence_, {}, {}, {}, {});
+    // Internal spends have no relative height/mtp (any metadata values work).
+    return is_locked(metadata.height, metadata.median_time_past);
 }
 
 bool input::reserved_hash(hash_digest& out) const NOEXCEPT
diff --git a/src/chain/transaction.cpp b/src/chain/transaction.cpp
index 13d341b624..f90f6ad928 100644
--- a/src/chain/transaction.cpp
+++ b/src/chain/transaction.cpp
@@ -1151,6 +1151,18 @@ bool transaction::is_immature(size_t height) const NOEXCEPT
     return !std::all_of(inputs_->begin(), inputs_->end(), mature);
 }
 
+bool transaction::is_internal_lock(const input& in) const NOEXCEPT
+{
+    // BIP68: not applied to the sequence of the input of a coinbase.
+    BC_ASSERT(!is_coinbase());
+
+    // BIP68: applied to txs with a version greater than or equal to two.
+    if (version_ < relative_locktime_min_version)
+        return false;
+
+    return in.is_internal_lock();
+}
+
 bool transaction::is_locked(size_t height,
     uint32_t median_time_past) const NOEXCEPT
 {