diff --git a/include/bitcoin/system/chain/block.hpp b/include/bitcoin/system/chain/block.hpp
index 834a1ac91b..c80c406a32 100644
--- a/include/bitcoin/system/chain/block.hpp
+++ b/include/bitcoin/system/chain/block.hpp
@@ -98,6 +98,7 @@ class BC_API block
     bool is_segregated() const NOEXCEPT;
     size_t serialized_size(bool witness) const NOEXCEPT;
     size_t signature_operations(bool bip16, bool bip141) const NOEXCEPT;
+    size_t segregated() const NOEXCEPT;
 
     /// Computed malleation properties.
     bool is_malleable() const NOEXCEPT;
diff --git a/include/bitcoin/system/error/macros.hpp b/include/bitcoin/system/error/macros.hpp
index bebea1cf94..9bb8b326f4 100644
--- a/include/bitcoin/system/error/macros.hpp
+++ b/include/bitcoin/system/error/macros.hpp
@@ -57,6 +57,7 @@ class BC_API cat##_category \
     static const message_map<cat##_t> messages; \
 public: \
     static const cat##_category singleton; \
+    static bool contains(const std::error_code& ec) noexcept; \
     virtual const char* name() const noexcept; \
     virtual std::string message(int condition) const noexcept; \
     virtual std::error_condition default_error_condition(int value) const noexcept; \
@@ -74,6 +75,7 @@ class BC_API cat##_category \
     static const message_map<cat##_t> messages; \
 public: \
     static const cat##_category singleton; \
+    static bool contains(const std::error_code& ec) noexcept; \
     virtual const char* name() const noexcept; \
     virtual std::string message(int condition) const noexcept; \
     virtual std::error_condition default_error_condition(int value) const noexcept; \
@@ -84,6 +86,10 @@ std::error_condition make_error_condition(cat##_t value) noexcept
 
 #define DEFINE_ERROR_T_CATEGORY(cat, category_name, unmapped) \
 const cat##_category cat##_category::singleton; \
+bool cat##_category::contains(const std::error_code& ec) noexcept \
+{ \
+    return is_zero(std::strcmp(ec.category().name(), category_name)); \
+} \
 const char* cat##_category::name() const noexcept \
 { \
     return category_name; \
diff --git a/src/chain/block.cpp b/src/chain/block.cpp
index 6b1b5dc40b..33dff1d784 100644
--- a/src/chain/block.cpp
+++ b/src/chain/block.cpp
@@ -587,6 +587,16 @@ bool block::is_segregated() const NOEXCEPT
     return std::any_of(txs_->begin(), txs_->end(), segregated);
 }
 
+size_t block::segregated() const NOEXCEPT
+{
+    const auto count_segregated = [](const auto& tx) NOEXCEPT
+    {
+        return tx->is_segregated();
+    };
+
+    return std::count_if(txs_->begin(), txs_->end(), count_segregated);
+}
+
 // The witness merkle root is obtained from wtxids, subject to malleation just
 // as the txs commitment. However, since tx duplicates are precluded by the
 // malleable32 (or complete) block check, there is no opportunity for this.
@@ -600,6 +610,10 @@ bool block::is_invalid_witness_commitment() const NOEXCEPT
     if (coinbase->inputs_ptr()->empty())
         return false;
 
+    // If no block tx has witness data the commitment is optional (bip141).
+    if (!is_segregated())
+        return false;
+
     // If there is a valid commitment, return false (valid).
     // Coinbase input witness must be 32 byte witness reserved value (bip141).
     // Last output of commitment pattern holds the committed value (bip141).
@@ -610,10 +624,8 @@ bool block::is_invalid_witness_commitment() const NOEXCEPT
                 if (committed == sha256::double_hash(
                     generate_merkle_root(true), reserved))
                     return false;
-    
-    // If no valid commitment, return true (invalid) if segregated.
-    // If no block tx has witness data the commitment is optional (bip141).
-    return is_segregated();
+
+    return true;
 }
 
 //*****************************************************************************
diff --git a/test/chain/block.cpp b/test/chain/block.cpp
index f177ca3004..1ec88dfa67 100644
--- a/test/chain/block.cpp
+++ b/test/chain/block.cpp
@@ -460,6 +460,7 @@ BOOST_AUTO_TEST_CASE(block__hash__default__matches_header_hash)
 // is_malleable
 // is_segregated
 // serialized_size
+// segregated
 
 // validation (public)
 // ----------------------------------------------------------------------------
diff --git a/test/error/error.cpp b/test/error/error.cpp
index 207a8ea702..cf494cf49e 100644
--- a/test/error/error.cpp
+++ b/test/error/error.cpp
@@ -40,7 +40,7 @@ BOOST_AUTO_TEST_CASE(error_t__code__message_overflow__default_message)
 // Overflows can be cast in, and value retained, and yield default message.
 BOOST_AUTO_TEST_CASE(error_t__code__value_overflow__default_message)
 {
-    const auto overflow = static_cast<int>(error::error_last);
+    constexpr auto overflow = static_cast<int>(error::error_last);
     const auto ec = code(static_cast<error::error_t>(overflow));
     BOOST_REQUIRE(ec);
     BOOST_REQUIRE_EQUAL(ec.message(), default_message);
@@ -108,6 +108,14 @@ BOOST_AUTO_TEST_CASE(error_t__code__category_name__expected)
 {
     BOOST_REQUIRE_EQUAL(code().category().name(), system_category_name);
     BOOST_REQUIRE_EQUAL(code(error::success).category().name(), bitcoin_category_name);
+    BOOST_REQUIRE_NE(code(error::script_success).category().name(), code(error::success).category().name());
+}
+
+BOOST_AUTO_TEST_CASE(error_t__code__category_contains__expected)
+{
+    BOOST_REQUIRE(system::error::error_category::contains(system::error::success));
+    BOOST_REQUIRE(!system::error::script_error_category::contains(system::error::success));
+    BOOST_REQUIRE(system::error::script_error_category::contains(system::error::script_success));
 }
 
 BOOST_AUTO_TEST_CASE(error_t__code__default_error_condition_category_name__expected)