diff --git a/include/quicr/detail/ctrl_message_types.h b/include/quicr/detail/ctrl_message_types.h
index 2fdc9db9..45b938fb 100644
--- a/include/quicr/detail/ctrl_message_types.h
+++ b/include/quicr/detail/ctrl_message_types.h
@@ -408,8 +408,9 @@ namespace quicr::messages {
         {
             if constexpr (std::is_arithmetic_v<T> || std::is_enum_v<T>) {
                 if (static_cast<uint64_t>(type) % 2 == 0) {
-                    UintVar u_value(static_cast<uint64_t>(value));
-                    return Bytes{ u_value.begin(), u_value.end() };
+                    const std::uint64_t val = static_cast<std::uint64_t>(value);
+                    auto* val_bytes = reinterpret_cast<const std::uint8_t*>(&val);
+                    return Bytes{ val_bytes, val_bytes + sizeof(val) };
                 }
             }
 
@@ -459,7 +460,10 @@ namespace quicr::messages {
         {
             if constexpr (std::is_arithmetic_v<T>) {
                 if (static_cast<std::uint64_t>(type) % 2 == 0) {
-                    return static_cast<T>(UintVar(extensions.at(static_cast<std::uint64_t>(type))).Get());
+                    std::uint64_t val = 0;
+                    const auto& bytes = extensions.at(static_cast<std::uint64_t>(type));
+                    std::memcpy(&val, bytes.data(), std::min(bytes.size(), sizeof(val)));
+                    return static_cast<T>(val);
                 }
             }
 
@@ -477,7 +481,10 @@ namespace quicr::messages {
         {
             if constexpr (std::is_arithmetic_v<T>) {
                 if (static_cast<std::uint64_t>(type) % 2 == 0) {
-                    return static_cast<T>(UintVar(immutable_extensions.at(static_cast<std::uint64_t>(type))).Get());
+                    std::uint64_t val = 0;
+                    const auto& bytes = immutable_extensions.at(static_cast<std::uint64_t>(type));
+                    std::memcpy(&val, bytes.data(), std::min(bytes.size(), sizeof(val)));
+                    return static_cast<T>(val);
                 }
             }
 
@@ -523,8 +530,9 @@ namespace quicr::messages {
         {
             if constexpr (std::is_arithmetic_v<T> || std::is_enum_v<T>) {
                 if (static_cast<uint64_t>(type) % 2 == 0) {
-                    UintVar u_value(static_cast<uint64_t>(value));
-                    parameters.push_back({ type, Bytes{ u_value.begin(), u_value.end() } });
+                    const std::uint64_t val = static_cast<std::uint64_t>(value);
+                    auto* val_bytes = reinterpret_cast<const std::uint8_t*>(&val);
+                    parameters.push_back({ type, Bytes{ val_bytes, val_bytes + sizeof(val) } });
                     return *this;
                 }
             }
@@ -584,7 +592,9 @@ namespace quicr::messages {
 
             if constexpr (std::is_arithmetic_v<T>) {
                 if (static_cast<std::uint64_t>(type) % 2 == 0) {
-                    return static_cast<T>(UintVar(bytes).Get());
+                    std::uint64_t val = 0;
+                    std::memcpy(&val, bytes.data(), std::min(bytes.size(), sizeof(val)));
+                    return static_cast<T>(val);
                 }
             }
 
diff --git a/test/moq_ctrl_messages.cpp b/test/moq_ctrl_messages.cpp
index 8c019870..37610b0f 100644
--- a/test/moq_ctrl_messages.cpp
+++ b/test/moq_ctrl_messages.cpp
@@ -810,3 +810,79 @@ TEST_CASE("uint16_t encode/decode")
 {
     IntegerEncodeDecode<std::uint16_t>(true);
 }
+
+TEST_CASE("KeyValuePair even-type round-trip preserves values")
+{
+    const std::vector<std::uint64_t> test_values = {
+        0,      1,
+        63, // Max 1-byte varint
+        64, // Min 2-byte varint
+        127,    128, 255,
+        16383, // Max 2-byte varint
+        16384, // Min 4-byte varint
+        100000,
+    };
+
+    for (const auto value : test_values) {
+        CAPTURE(value);
+
+        Parameters params;
+        params.Add(ParameterType::kDeliveryTimeout, value);
+
+        Bytes buffer;
+        buffer << params;
+
+        // Should have encoded as uintvar.
+        UintVar expected(value);
+        Bytes expected_bytes{ expected.begin(), expected.end() };
+        REQUIRE(buffer.size() >= expected_bytes.size());
+        Bytes tail(buffer.end() - expected_bytes.size(), buffer.end());
+        CHECK_EQ(tail, expected_bytes);
+
+        Parameters out;
+        BytesSpan span{ buffer };
+        span >> out;
+
+        // Roundtrip.
+        CHECK_NOTHROW(out.Get<std::uint64_t>(ParameterType::kDeliveryTimeout));
+        CHECK_EQ(out.Get<std::uint64_t>(ParameterType::kDeliveryTimeout), value);
+    }
+}
+
+TEST_CASE("TrackExtensions even-type round-trip preserves values")
+{
+    const std::vector<std::uint64_t> test_values = {
+        0,      1,
+        63, // Max 1-byte varint
+        64, // Min 2-byte varint
+        127,    128, 255,
+        16383, // Max 2-byte varint
+        16384, // Min 4-byte varint
+        100000,
+    };
+
+    for (const auto value : test_values) {
+        CAPTURE(value);
+
+        TrackExtensions ext;
+        ext.Add(ExtensionType::kDeliveryTimeout, value);
+
+        Bytes buffer;
+        buffer << ext;
+
+        // Should have been encoded as uintvar.
+        UintVar expected(value);
+        Bytes expected_bytes{ expected.begin(), expected.end() };
+        REQUIRE(buffer.size() >= expected_bytes.size());
+        Bytes tail(buffer.end() - expected_bytes.size(), buffer.end());
+        CHECK_EQ(tail, expected_bytes);
+
+        TrackExtensions out;
+        BytesSpan span{ buffer };
+        span >> out;
+
+        // Roundtrip.
+        CHECK_NOTHROW(out.Get<std::uint64_t>(ExtensionType::kDeliveryTimeout));
+        CHECK_EQ(out.Get<std::uint64_t>(ExtensionType::kDeliveryTimeout), value);
+    }
+}