diff --git a/src/core/file_sys/kernel_executable.cpp b/src/core/file_sys/kernel_executable.cpp
index 371300684a..76313679d2 100644
--- a/src/core/file_sys/kernel_executable.cpp
+++ b/src/core/file_sys/kernel_executable.cpp
@@ -147,7 +147,7 @@ std::vector<u32> KIP::GetKernelCapabilities() const {
 }
 
 s32 KIP::GetMainThreadPriority() const {
-    return header.main_thread_priority;
+    return static_cast<s32>(header.main_thread_priority);
 }
 
 u32 KIP::GetMainThreadStackSize() const {
diff --git a/src/core/file_sys/program_metadata.cpp b/src/core/file_sys/program_metadata.cpp
index 7310b36026..1d6c309621 100644
--- a/src/core/file_sys/program_metadata.cpp
+++ b/src/core/file_sys/program_metadata.cpp
@@ -52,14 +52,14 @@ Loader::ResultStatus ProgramMetadata::Load(VirtualFile file) {
 }
 
 void ProgramMetadata::LoadManual(bool is_64_bit, ProgramAddressSpaceType address_space,
-                                 u8 main_thread_prio, u8 main_thread_core,
+                                 s32 main_thread_prio, u32 main_thread_core,
                                  u32 main_thread_stack_size, u64 title_id,
                                  u64 filesystem_permissions,
                                  KernelCapabilityDescriptors capabilities) {
     npdm_header.has_64_bit_instructions.Assign(is_64_bit);
     npdm_header.address_space_type.Assign(address_space);
-    npdm_header.main_thread_priority = main_thread_prio;
-    npdm_header.main_thread_cpu = main_thread_core;
+    npdm_header.main_thread_priority = static_cast<u8>(main_thread_prio);
+    npdm_header.main_thread_cpu = static_cast<u8>(main_thread_core);
     npdm_header.main_stack_size = main_thread_stack_size;
     aci_header.title_id = title_id;
     aci_file_access.permissions = filesystem_permissions;
diff --git a/src/core/file_sys/program_metadata.h b/src/core/file_sys/program_metadata.h
index 88ec97d85f..f8759a3968 100644
--- a/src/core/file_sys/program_metadata.h
+++ b/src/core/file_sys/program_metadata.h
@@ -47,8 +47,8 @@ public:
     Loader::ResultStatus Load(VirtualFile file);
 
     // Load from parameters instead of NPDM file, used for KIP
-    void LoadManual(bool is_64_bit, ProgramAddressSpaceType address_space, u8 main_thread_prio,
-                    u8 main_thread_core, u32 main_thread_stack_size, u64 title_id,
+    void LoadManual(bool is_64_bit, ProgramAddressSpaceType address_space, s32 main_thread_prio,
+                    u32 main_thread_core, u32 main_thread_stack_size, u64 title_id,
                     u64 filesystem_permissions, KernelCapabilityDescriptors capabilities);
 
     bool Is64BitProgram() const;