diff --git a/src/common/mmap.h b/src/common/mmap.h
index 9e076b5..5a8a9ce 100644
--- a/src/common/mmap.h
+++ b/src/common/mmap.h
@@ -19,4 +19,12 @@ struct stream {
         p += sizeof(T) * len;
         return s;
     }
+    template <typename T>
+    void operator=(const T &v) {
+        memcpy(p, (uint8_t*)&v, sizeof(v));
+        p += sizeof(v);
+    }
+    void skip(size_t len) {
+        p += len;
+    }
 };
diff --git a/src/common/types.h b/src/common/types.h
index ec72cc7..5bd57e1 100644
--- a/src/common/types.h
+++ b/src/common/types.h
@@ -327,6 +327,20 @@ struct ModificatorMask
 
 #pragma pack(push, 1)
 struct pak {
+    static constexpr uint32_t default_block_size = 0x4000;
+
+    struct segment {
+        // some file offset? trash? crc? m1 has zlib crc table (png)?
+        uint32_t unk1;
+        uint32_t algorithm;
+        uint32_t offset;
+    };
+    struct file_description {
+        char name[0x50];
+        uint32_t offset;
+        uint32_t size;
+    };
+
     uint32_t magic;
     uint16_t unk0;
     uint32_t n_files;
@@ -334,20 +348,4 @@ struct pak {
     uint32_t block_size;
     uint32_t unk1;
 };
-struct file_description {
-    const char name[0x50];
-    uint32_t offset;
-    uint32_t size;
-};
-struct segment {
-    enum decode_algorithm : uint32_t {
-        none = 0x0,
-        // none = 0x1, // ?
-    };
-
-    // some file offset? trash? crc? m1 has zlib crc table (png)?
-    uint32_t unk1;
-    decode_algorithm algorithm;
-    uint32_t offset;
-};
 #pragma pack(pop)
diff --git a/src/unpaker/unpaker.cpp b/src/unpaker/unpaker.cpp
index be90d4c..2e6bb6c 100644
--- a/src/unpaker/unpaker.cpp
+++ b/src/unpaker/unpaker.cpp
@@ -44,8 +44,8 @@ void unpack_file(path fn) {
     primitives::templates2::mmap_file<uint8_t> f{fn};
     stream s{f};
     pak p = s;
-    auto descs = s.span<file_description>(p.n_files);
-    auto segments = s.span<segment>(p.n_blocks);
+    auto descs = s.span<pak::file_description>(p.n_files);
+    auto segments = s.span<pak::segment>(p.n_blocks);
     std::vector<uint8_t> decoded;
     decoded.resize((segments.size() + 1) * p.block_size * 4);
     auto pp = decoded.data();