diff --git a/ultramodern/src/pfs.cpp b/ultramodern/src/pfs.cpp
index f76741f..6ba363d 100644
--- a/ultramodern/src/pfs.cpp
+++ b/ultramodern/src/pfs.cpp
@@ -227,7 +227,7 @@ extern "C" s32 osPfsDeleteFile(RDRAM_ARG PTR(OSPfs) pfs_, u16 company_code, u32
     return PFS_ERR_INVALID;
 }
 
-extern "C" s32 osPfsReadWriteFile(RDRAM_ARG PTR(OSPfs) pfs_, s32 file_no, u8 flag, int offset, int size_in_bytes, u8* data_buffer) {
+extern "C" s32 osPfsReadWriteFile(RDRAM_ARG PTR(OSPfs) pfs_, s32 file_no, u8 flag, int offset, int nbytes, u8* data_buffer) {
     pfs_state_t pak;
 
     const auto filename = pfs_file_path(file_no);
@@ -243,15 +243,12 @@ extern "C" s32 osPfsReadWriteFile(RDRAM_ARG PTR(OSPfs) pfs_, s32 file_no, u8 fla
         return PFS_ERR_INVALID;
     }
 
-    std::vector<u8> swap_buffer(size_in_bytes);
-    if (flag == 0) {
+    if (flag == PFS_READ) {
         pak.file.seekg(offset, std::ios::beg);
-        pak.file.read((char*)swap_buffer.data(), size_in_bytes);
-        ByteSwapCopy(data_buffer, swap_buffer.data(), size_in_bytes);
+        pak.file.read((char*)data_buffer, nbytes);
     } else {
-        ByteSwapCopy(swap_buffer.data(), data_buffer, size_in_bytes);
         pak.file.seekp(offset, std::ios::beg);
-        pak.file.write((char*)swap_buffer.data(), size_in_bytes);
+        pak.file.write((const char*)data_buffer, nbytes);
     }
 
     pak.file.close();
diff --git a/ultramodern/src/pfs.hpp b/ultramodern/src/pfs.hpp
index 46891c2..5a83fea 100644
--- a/ultramodern/src/pfs.hpp
+++ b/ultramodern/src/pfs.hpp
@@ -105,27 +105,5 @@ void pfs_header_read(pfs_header_t& hdr, u8 file_index) {
     pak.header.close();
 }
 
-void Pfs_ByteSwapFile(u8* buffer, size_t size) {
-    uint8_t c0, c1, c2, c3;
-
-    for (size_t i = 0; i < size; i += 4) {
-        c0 = buffer[i + 0];
-        c1 = buffer[i + 1];
-        c2 = buffer[i + 2];
-        c3 = buffer[i + 3];
-
-        buffer[i + 3] = c0;
-        buffer[i + 2] = c1;
-        buffer[i + 1] = c2;
-        buffer[i + 0] = c3;
-    }
-}
-
-void ByteSwapCopy(uint8_t* dst, const uint8_t* src, size_t nbytes) {
-    for (size_t i = 0; i < nbytes; i++) {
-        dst[i] = src[i ^ 3];
-    }
-}
-
 #endif // __ULTRAMODERN_PFS_HPP__