diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3eb8dd533..8704dfdbd 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -68,6 +68,14 @@ if(BUILD_TESTING)
         ${CMAKE_CURRENT_SOURCE_DIR}/core/shader/recompiler)
     add_test(NAME shader_cache_file_read COMMAND shader_cache_file_read_tests)
     set_tests_properties(shader_cache_file_read PROPERTIES TIMEOUT 20)
+    add_test_executable(request_serializer_tests
+        ${CMAKE_CURRENT_SOURCE_DIR}/core/shader/recompiler/tests/RequestSerializerTests.cpp
+        ${CMAKE_CURRENT_SOURCE_DIR}/core/shader/recompiler/ControlFlow/src/RequestSerializer.cpp)
+    target_include_directories(request_serializer_tests PRIVATE
+        ${CMAKE_CURRENT_SOURCE_DIR}/core/shader/recompiler
+        ${CMAKE_CURRENT_SOURCE_DIR}/core/shader/recompiler/ControlFlow/include)
+    add_test(NAME request_serializer COMMAND request_serializer_tests)
+    set_tests_properties(request_serializer PROPERTIES TIMEOUT 20)
     find_package(Python3 QUIET COMPONENTS Interpreter)
     if(Python3_Interpreter_FOUND)
         add_test(NAME pr_overlap_encoding COMMAND ${Python3_EXECUTABLE}
diff --git a/core/shader/recompiler/ControlFlow/src/RequestSerializer.cpp b/core/shader/recompiler/ControlFlow/src/RequestSerializer.cpp
index 217d54eee..eb3c70970 100644
--- a/core/shader/recompiler/ControlFlow/src/RequestSerializer.cpp
+++ b/core/shader/recompiler/ControlFlow/src/RequestSerializer.cpp
@@ -153,6 +153,8 @@ public:
 
     bool ReadBool() { return ReadU8() != 0u; }
 
+    std::uint64_t Remaining() const { return m_data.size() - m_offset; }
+
     std::uint32_t ReadU32() {
         std::uint32_t value = 0u;
         for (std::uint32_t i = 0; i < 4u; i++) {
@@ -808,7 +810,15 @@ DeserializedRequest RequestSerializer::Deserialize(std::string_view text) const
     if (version >= 17u) result.request.target.registrationModules = reader.ReadBool();
     if (version >= 17u) result.request.target.registrationWordLimit = reader.ReadU32();
     if (version >= 18u) result.request.target.vertexSubgroups = reader.ReadBool();
-    if (version >= 21u) result.request.target.float16DenormPreserve = reader.ReadBool();
+    if (version >= 21u) {
+        if (reader.Remaining() == 1u) {
+            const auto float16DenormPreserve = reader.ReadU8();
+            if (float16DenormPreserve > 1u) throw std::runtime_error("RequestSerializer: invalid float16DenormPreserve value");
+            result.request.target.float16DenormPreserve = float16DenormPreserve != 0u;
+        } else if (reader.Remaining() != 0u) {
+            throw std::runtime_error("RequestSerializer: unexpected trailing data");
+        }
+    }
     return result;
 }
 
diff --git a/core/shader/recompiler/tests/RequestSerializerTests.cpp b/core/shader/recompiler/tests/RequestSerializerTests.cpp
new file mode 100644
index 000000000..9066ce55c
--- /dev/null
+++ b/core/shader/recompiler/tests/RequestSerializerTests.cpp
@@ -0,0 +1,33 @@
+#include "ControlFlow/RequestSerializer.hpp"
+
+#include <cstdlib>
+#include <stdexcept>
+
+namespace {
+
+constexpr char kHistoricalVersion21[] =
+    "NVNQQRUAAAAFAAADAAAAAAABAAAAAAAAAAAAgb8AAAAAAAAAAAAAAAAAAAAAQAAAAAgAAAADAAAAAAAAAN+bVxPgrGgk776t3gABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAJAAAAAAAAAOQAAAAAAAAAAAAAAAAAAAAAAQEAAAEAAAAAAAAAAAAFAAAAAAAEAAAAAAAAABI0VngAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAALAAAAEAAAAEAAAAAAAAF4VjQSAQEBOTAAAAA=";
+
+void Require(bool condition) {
+    if (!condition) std::abort();
+}
+
+}
+
+int main() {
+    const ShaderRecompiler::RequestSerializer serializer;
+
+    const auto historical = serializer.Deserialize(kHistoricalVersion21);
+    Require(!historical.request.target.float16DenormPreserve);
+
+    ShaderRecompiler::RecompileRequest request{};
+    request.target.float16DenormPreserve = false;
+    const auto withoutPreserve = serializer.Deserialize(serializer.Serialize(request));
+    Require(!withoutPreserve.request.target.float16DenormPreserve);
+
+    request.target.float16DenormPreserve = true;
+    const auto withPreserve = serializer.Deserialize(serializer.Serialize(request));
+    Require(withPreserve.request.target.float16DenormPreserve);
+
+    return 0;
+}