diff --git a/CMakeLists.txt b/CMakeLists.txt
index 02621d8336..467623a309 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -422,8 +422,12 @@ set(TESTFILTER "" CACHE STRING "Filter string for ctest to selectively only run
 
 include(px4_add_gtest)
 if(BUILD_TESTING)
-	# Setting FUZZTEST_FUZZING_MODE=on enables ASAN, and is only supported with Clang
-	if (("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang") OR ("${CMAKE_CXX_COMPILER_ID}" MATCHES "AppleClang"))
+	# Setting FUZZTEST_FUZZING_MODE=on enables ASAN, and is only supported with Clang.
+	# clang-cl on Windows uses the MSVC driver: ASAN there is incompatible with the
+	# debug C runtime (/MDd) emitted by CMake's Debug config, so keep fuzzing mode
+	# off on that combination and just compile fuzztest as a plain dependency.
+	if ((("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang") OR ("${CMAKE_CXX_COMPILER_ID}" MATCHES "AppleClang"))
+		AND NOT (WIN32 AND "${CMAKE_CXX_SIMULATE_ID}" STREQUAL "MSVC"))
 		set(FUZZTEST_FUZZING_MODE ON)
 	endif()
 	add_subdirectory(test)
diff --git a/src/lib/drivers/led/led.cpp b/src/lib/drivers/led/led.cpp
index afbdc11565..e472e859e3 100644
--- a/src/lib/drivers/led/led.cpp
+++ b/src/lib/drivers/led/led.cpp
@@ -64,7 +64,7 @@ public:
 	~LED() override = default;
 
 	int	init() override;
-	int	ioctl(cdev::file_t *filp, int cmd, uintptr_t arg) override;
+	int	ioctl(cdev::file_t *filp, int cmd, unsigned long arg) override;
 };
 
 LED::LED() : CDev(LED0_DEVICE_PATH)
@@ -86,7 +86,7 @@ LED::init()
 }
 
 int
-LED::ioctl(cdev::file_t *filp, int cmd, uintptr_t arg)
+LED::ioctl(cdev::file_t *filp, int cmd, unsigned long arg)
 {
 	int result = OK;