diff --git a/core/libs/prx/libSceHmd/Hmd.hpp b/core/libs/prx/libSceHmd/Hmd.hpp
index eb2f77625f..31cf038dbb 100644
--- a/core/libs/prx/libSceHmd/Hmd.hpp
+++ b/core/libs/prx/libSceHmd/Hmd.hpp
@@ -51,6 +51,11 @@ static_assert(offsetof(DeviceInformation, hmuMount) == 24);
 
 }
 
+struct HmdFieldOfView;
+struct HmdEyeOffset;
+struct HmdInertialSensorData;
+struct HmdAssemblyError;
+
 extern "C" {
 std::int32_t APS5_VABI sceHmdInitialize(const Hmd::InitializeParam* param);
 std::int32_t APS5_VABI sceHmdInitialize315(const Hmd::InitializeParam* param);
@@ -69,10 +74,10 @@ int APS5_VABI sceHmdReprojectionQueryGarlicBuffAlign(void);
 int APS5_VABI sceHmdReprojectionQueryGarlicBuffSize(void);
 int APS5_VABI sceHmdReprojectionQueryOnionBuffAlign(void);
 int APS5_VABI sceHmdReprojectionQueryOnionBuffSize(void);
-int APS5_VABI sceHmdGetFieldOfView(std::int32_t handle, void* fieldOfView);
-int APS5_VABI sceHmdGet2DEyeOffset(std::int32_t handle, void* leftOffset, void* rightOffset);
-int APS5_VABI sceHmdGetInertialSensorData(std::int32_t handle, void* data, std::int32_t count);
-int APS5_VABI sceHmdGetAssyError(void* data);
+int APS5_VABI sceHmdGetFieldOfView(std::int32_t handle, HmdFieldOfView* fieldOfView);
+int APS5_VABI sceHmdGet2DEyeOffset(std::int32_t handle, HmdEyeOffset* leftOffset, HmdEyeOffset* rightOffset);
+int APS5_VABI sceHmdGetInertialSensorData(std::int32_t handle, HmdInertialSensorData* data, std::uint32_t count);
+int APS5_VABI sceHmdGetAssyError(HmdAssemblyError* data);
 }
 
 #endif
diff --git a/core/libs/tests/GuestHmd.cpp b/core/libs/tests/GuestHmd.cpp
index 203775d1fd..230395afb9 100644
--- a/core/libs/tests/GuestHmd.cpp
+++ b/core/libs/tests/GuestHmd.cpp
@@ -42,10 +42,10 @@ void CheckHandleQueries(std::int32_t expected) {
     std::memset(sensor, 0x5a, sizeof(sensor));
     for (const auto handle : {0, -1, 1, 0x0f000000}) {
         Require(sceHmdGetFieldOfView(handle, nullptr) == Hmd::ParameterNull, "null field of view accepted");
-        Require(sceHmdGetFieldOfView(handle, fieldOfView) == expected, "field of view without a headset");
-        Require(sceHmdGet2DEyeOffset(handle, left, right) == expected, "eye offset without a headset");
+        Require(sceHmdGetFieldOfView(handle, reinterpret_cast<HmdFieldOfView*>(fieldOfView)) == expected, "field of view without a headset");
+        Require(sceHmdGet2DEyeOffset(handle, reinterpret_cast<HmdEyeOffset*>(left), reinterpret_cast<HmdEyeOffset*>(right)) == expected, "eye offset without a headset");
         Require(sceHmdGet2DEyeOffset(handle, nullptr, nullptr) == expected, "eye offset with null outputs");
-        Require(sceHmdGetInertialSensorData(handle, sensor, 1) == expected, "sensor data without a headset");
+        Require(sceHmdGetInertialSensorData(handle, reinterpret_cast<HmdInertialSensorData*>(sensor), 1) == expected, "sensor data without a headset");
     }
     for (const auto* bytes : {left, right, fieldOfView}) {
         for (std::size_t index = 0; index < 16; ++index) Require(bytes[index] == 0x5a, "a refused query wrote its output");
@@ -57,7 +57,7 @@ void CheckAssyError(std::int32_t expected) {
     unsigned char data[32];
     std::memset(data, 0x5a, sizeof(data));
     Require(sceHmdGetAssyError(nullptr) == Hmd::ParameterNull, "null assembly error output accepted");
-    Require(sceHmdGetAssyError(data) == expected, "assembly error query without a headset");
+    Require(sceHmdGetAssyError(reinterpret_cast<HmdAssemblyError*>(data)) == expected, "assembly error query without a headset");
     for (const auto byte : data) Require(byte == 0x5a, "a refused assembly error query wrote its output");
 }
 
diff --git a/core/libs/tests/GuestNpWebApi2.cpp b/core/libs/tests/GuestNpWebApi2.cpp
index 7bd8327e2b..1adccd989d 100644
--- a/core/libs/tests/GuestNpWebApi2.cpp
+++ b/core/libs/tests/GuestNpWebApi2.cpp
@@ -92,7 +92,7 @@ int main() {
     Require(presence > 0 && sceNpWebApi2GetMemoryPoolStats(presence, &stats) == 0 && stats.pool_size == 0x2000);
     for (const int created : {internal, internal2, presence}) {
         Require(sceNpWebApi2Terminate(created) == 0);
-        Require(Throws([&] { sceNpWebApi2GetMemoryPoolStats(created, &stats); }));
+        Require(sceNpWebApi2GetMemoryPoolStats(created, &stats) == invalidContext);
     }
     return 0;
 }