diff --git a/src/ofbx.cpp b/src/ofbx.cpp
index 4e06ecb..9f75a2e 100644
--- a/src/ofbx.cpp
+++ b/src/ofbx.cpp
@@ -4046,7 +4046,7 @@ bool Scene::finalize() {
 	return true;
 }
 
-IScene* load(const u8* data, u64 size, u16 flags, JobProcessor job_processor, void* job_user_ptr)
+IScene* load(const u8* data, usize size, u16 flags, JobProcessor job_processor, void* job_user_ptr)
 {
 	std::unique_ptr<Scene> scene(new Scene());
 	scene->m_data.resize(size);
diff --git a/src/ofbx.h b/src/ofbx.h
index 94c0d6a..c9d87b0 100644
--- a/src/ofbx.h
+++ b/src/ofbx.h
@@ -21,6 +21,7 @@ static_assert(sizeof(u32) == 4, "u32 is not 4 bytes");
 static_assert(sizeof(u64) == 8, "u64 is not 8 bytes");
 static_assert(sizeof(i64) == 8, "i64 is not 8 bytes");
 
+typedef decltype(sizeof(0)) usize;
 
 using JobFunction = void (*)(void*);
 using JobProcessor = void (*)(JobFunction, void*, void*, u32, u32);
@@ -756,7 +757,7 @@ struct IScene
 };
 
 
-IScene* load(const u8* data, u64 size, u16 flags, JobProcessor job_processor = nullptr, void* job_user_ptr = nullptr);
+IScene* load(const u8* data, usize size, u16 flags, JobProcessor job_processor = nullptr, void* job_user_ptr = nullptr);
 const char* getError();
 double fbxTimeToSeconds(i64 value);
 i64 secondsToFbxTime(double value);