diff --git a/src/xenia/vfs/devices/stfs_container_device.cc b/src/xenia/vfs/devices/stfs_container_device.cc
index 52c7b3a3f..7160ddd4f 100644
--- a/src/xenia/vfs/devices/stfs_container_device.cc
+++ b/src/xenia/vfs/devices/stfs_container_device.cc
@@ -118,6 +118,8 @@ StfsContainerDevice::Error StfsContainerDevice::MapFiles() {
     return header_result;
   }
 
+  mmap_total_size_ = header_map->size();
+
   // If the STFS package is a single file, the header is self contained and
   // we don't need to map any extra files.
   // NOTE: data_file_count is 0 for STFS and 1 for SVOD
@@ -157,8 +159,10 @@ StfsContainerDevice::Error StfsContainerDevice::MapFiles() {
     if (!data) {
       XELOGI("Failed to map SVOD file {}.", xe::path_to_utf8(path));
       mmap_.clear();
+      mmap_total_size_ = 0;
       return Error::kErrorReadError;
     }
+    mmap_total_size_ += data->size();
     mmap_.emplace(std::make_pair(i, std::move(data)));
   }
   XELOGI("SVOD successfully mapped {} files.", fragment_files.size());
@@ -472,7 +476,7 @@ StfsContainerDevice::Error StfsContainerDevice::ReadSTFS() {
   uint32_t table_block_index = volume_descriptor.file_table_block_number();
   for (size_t n = 0; n < volume_descriptor.file_table_block_count; n++) {
     const uint8_t* p = data + BlockToOffsetSTFS(table_block_index);
-    for (size_t m = 0; m < 0x1000 / 0x40; m++) {
+    for (size_t m = 0; m < kSectorSize / 0x40; m++) {
       const uint8_t* name_buffer = p;  // 0x28b
       if (name_buffer[0] == 0) {
         // Done.
@@ -529,7 +533,7 @@ StfsContainerDevice::Error StfsContainerDevice::ReadSTFS() {
         size_t remaining_size = file_size;
         while (remaining_size && block_index) {
           size_t block_size =
-              std::min(static_cast<size_t>(0x1000), remaining_size);
+              std::min(static_cast<size_t>(kSectorSize), remaining_size);
           size_t offset = BlockToOffsetSTFS(block_index);
           entry->block_list_.push_back({0, offset, block_size});
           remaining_size -= block_size;
@@ -582,7 +586,7 @@ size_t StfsContainerDevice::BlockToOffsetSTFS(uint64_t block_index) {
     base *= kBlocksPerHashLevel[0];
   }
 
-  return xe::round_up(header_.header.header_size, 0x1000) + (block << 12);
+  return xe::round_up(header_.header.header_size, kSectorSize) + (block << 12);
 }
 
 StfsHashEntry StfsContainerDevice::GetBlockHash(const uint8_t* map_ptr,
diff --git a/src/xenia/vfs/devices/stfs_container_device.h b/src/xenia/vfs/devices/stfs_container_device.h
index eacd422fc..500b1ab21 100644
--- a/src/xenia/vfs/devices/stfs_container_device.h
+++ b/src/xenia/vfs/devices/stfs_container_device.h
@@ -15,6 +15,7 @@
 #include <string>
 
 #include "xenia/base/mapped_memory.h"
+#include "xenia/base/math.h"
 #include "xenia/base/string_util.h"
 #include "xenia/kernel/util/xex2_info.h"
 #include "xenia/vfs/device.h"
@@ -413,13 +414,23 @@ class StfsContainerDevice : public Device {
   uint32_t component_name_max_length() const override { return 40; }
 
   uint32_t total_allocation_units() const override {
-    return uint32_t(mmap_total_size_ / sectors_per_allocation_unit() /
+    return uint32_t(data_size() / sectors_per_allocation_unit() /
                     bytes_per_sector());
   }
   uint32_t available_allocation_units() const override { return 0; }
   uint32_t sectors_per_allocation_unit() const override { return 8; }
   uint32_t bytes_per_sector() const override { return 0x200; }
 
+  // Gives rough estimate of the size of the data in this container
+  // TODO: use allocated_block_count inside volume-descriptor?
+  size_t data_size() const {
+    if (header_.header.header_size) {
+      return mmap_total_size_ -
+             xe::round_up(header_.header.header_size, kSectorSize);
+    }
+    return mmap_total_size_ - sizeof(StfsHeader);
+  }
+
  private:
   const uint32_t kSectorSize = 0x1000;
   const uint32_t kBlocksPerHashLevel[3] = {170, 28900, 4913000};