diff --git a/tests/plugin_tests/chowdsp_plugin_state_test/ParamHolderTest.cpp b/tests/plugin_tests/chowdsp_plugin_state_test/ParamHolderTest.cpp
index a872c6ed..fb1e629b 100644
--- a/tests/plugin_tests/chowdsp_plugin_state_test/ParamHolderTest.cpp
+++ b/tests/plugin_tests/chowdsp_plugin_state_test/ParamHolderTest.cpp
@@ -3,21 +3,20 @@
 
 TEST_CASE ("ParamHolder Test", "[plugin][state]")
 {
-    SECTION ("add()")
-    {
-        chowdsp::ParamHolder params;
-        std::array<chowdsp::PercentParameter::Ptr, 2> floatParams {
-            chowdsp::PercentParameter::Ptr { "param3", "Param", 0.5f },
-            chowdsp::PercentParameter::Ptr { "param4", "Param", 0.5f },
-        };
-
-        chowdsp::BoolParameter::Ptr boolNested { "param1", "Param", false };
-        chowdsp::ChoiceParameter::Ptr choiceNested { "param2", "Param", juce::StringArray { "One", "Two" }, 0 };
-        chowdsp::ParamHolder nestedParams { &params };
-        nestedParams.add (boolNested, choiceNested);
+    std::array<chowdsp::PercentParameter::Ptr, 2> floatParams {
+        chowdsp::PercentParameter::Ptr { "param3", "Param", 0.5f },
+        chowdsp::PercentParameter::Ptr { "param4", "Param", 0.5f },
+    };
+    chowdsp::BoolParameter::Ptr boolNested { "param1", "Param", false };
+    chowdsp::ChoiceParameter::Ptr choiceNested { "param2", "Param", juce::StringArray { "One", "Two" }, 0 };
 
-        params.add (nestedParams, floatParams);
+    chowdsp::ParamHolder params;
+    chowdsp::ParamHolder nestedParams { &params };
+    nestedParams.add (boolNested, choiceNested);
+    params.add (nestedParams, floatParams);
 
+    SECTION ("add()")
+    {
         auto allParamIDs = [&params]
         {
             juce::StringArray allIDs;
@@ -31,4 +30,55 @@ TEST_CASE ("ParamHolder Test", "[plugin][state]")
         REQUIRE (allParamIDs.contains (floatParams[0]->paramID));
         REQUIRE (allParamIDs.contains (floatParams[1]->paramID));
     }
+
+    SECTION ("Serialize JSON")
+    {
+        using namespace chowdsp::ParameterTypeHelpers;
+        setValue (0.0f, *floatParams[0]);
+        setValue (1.0f, *floatParams[1]);
+        setValue (true, *boolNested);
+        setValue (1, *choiceNested);
+
+        const auto json_state = chowdsp::ParamHolder::serialize_json (params);
+        params.doForAllParameters ([] (auto& param, size_t) { setValue (getDefaultValue (param), param); });
+
+        REQUIRE (getValue (*floatParams[0]) == 0.5f);
+        REQUIRE (getValue (*floatParams[1]) == 0.5f);
+        REQUIRE (getValue (*boolNested) == false);
+        REQUIRE (getValue (*choiceNested) == 0);
+
+        chowdsp::ParamHolder::deserialize_json (json_state, params);
+        REQUIRE (getValue (*floatParams[0]) == 0.0f);
+        REQUIRE (getValue (*floatParams[1]) == 1.0f);
+        REQUIRE (getValue (*boolNested) == true);
+        REQUIRE (getValue (*choiceNested) == 1);
+    }
+
+    SECTION ("Serialize Bytes")
+    {
+        using namespace chowdsp::ParameterTypeHelpers;
+        setValue (0.0f, *floatParams[0]);
+        setValue (1.0f, *floatParams[1]);
+        setValue (true, *boolNested);
+        setValue (1, *choiceNested);
+
+        chowdsp::ChainedArenaAllocator arena { 128 };
+        chowdsp::ParamHolder::serialize (arena, params);
+        juce::MemoryBlock state {};
+        chowdsp::dump_serialized_bytes (state, arena);
+
+        params.doForAllParameters ([] (auto& param, size_t) { setValue (getDefaultValue (param), param); });
+
+        REQUIRE (getValue (*floatParams[0]) == 0.5f);
+        REQUIRE (getValue (*floatParams[1]) == 0.5f);
+        REQUIRE (getValue (*boolNested) == false);
+        REQUIRE (getValue (*choiceNested) == 0);
+
+        nonstd::span state_data = { (const std::byte*) state.getData(), state.getSize() };
+        chowdsp::ParamHolder::deserialize (state_data, params);
+        REQUIRE (getValue (*floatParams[0]) == 0.0f);
+        REQUIRE (getValue (*floatParams[1]) == 1.0f);
+        REQUIRE (getValue (*boolNested) == true);
+        REQUIRE (getValue (*choiceNested) == 1);
+    }
 }
diff --git a/tests/plugin_tests/chowdsp_presets_v2_test/PresetManagerTest.cpp b/tests/plugin_tests/chowdsp_presets_v2_test/PresetManagerTest.cpp
index ce81ae41..35114c4b 100644
--- a/tests/plugin_tests/chowdsp_presets_v2_test/PresetManagerTest.cpp
+++ b/tests/plugin_tests/chowdsp_presets_v2_test/PresetManagerTest.cpp
@@ -241,6 +241,27 @@ TEST_CASE ("Preset Manager Test", "[plugin][presets][state]")
         REQUIRE (presetMgr->getIsPresetDirty());
     }
 
+    SECTION ("Null State JSON Test")
+    {
+        static constexpr float otherValue = 0.15f;
+
+        chowdsp::json json_state;
+        {
+            ScopedPresetManager presetMgr {};
+
+            presetMgr.setFloatParam (otherValue);
+            REQUIRE (juce::approximatelyEqual (presetMgr.getFloatParam(), otherValue));
+
+            json_state = decltype (presetMgr.state)::serialize (presetMgr.state);
+        }
+
+        ScopedPresetManager presetMgr {};
+        decltype (presetMgr.state)::deserialize (json_state, presetMgr.state);
+        REQUIRE_MESSAGE (juce::approximatelyEqual (presetMgr.getFloatParam(), otherValue), "Preset state is overriding parameter state!");
+        REQUIRE (presetMgr->getCurrentPreset() == nullptr);
+        REQUIRE (presetMgr->getIsPresetDirty());
+    }
+
     SECTION ("Preset State Test")
     {
         static constexpr float testValue = 0.05f;
@@ -267,6 +288,32 @@ TEST_CASE ("Preset Manager Test", "[plugin][presets][state]")
         REQUIRE (presetMgr->getIsPresetDirty());
     }
 
+    SECTION ("Preset State JSON Test")
+    {
+        static constexpr float testValue = 0.05f;
+        static constexpr float otherValue = 0.15f;
+        auto preset = saveUserPreset ("test.preset", testValue);
+
+        chowdsp::json json_state;
+        {
+            ScopedPresetManager presetMgr {};
+            presetMgr->addPresets ({ chowdsp::presets::Preset { preset } });
+            presetMgr->loadPreset (presetMgr->getPresetTree().getRootNode().first_child->value.leaf());
+            REQUIRE (juce::approximatelyEqual (presetMgr.getFloatParam(), testValue));
+
+            presetMgr.setFloatParam (otherValue);
+            REQUIRE (juce::approximatelyEqual (presetMgr.getFloatParam(), otherValue));
+
+            json_state = decltype (presetMgr.state)::serialize (presetMgr.state);
+        }
+
+        ScopedPresetManager presetMgr {};
+        decltype (presetMgr.state)::deserialize (json_state, presetMgr.state);
+        REQUIRE_MESSAGE (juce::approximatelyEqual (presetMgr.getFloatParam(), otherValue), "Preset state is overriding parameter state!");
+        REQUIRE (*presetMgr->getCurrentPreset() == preset);
+        REQUIRE (presetMgr->getIsPresetDirty());
+    }
+
     SECTION ("Preset Undo/Redo Test")
     {
         static constexpr float testValue = 0.05f;