diff --git a/src/minivhd_internal.h b/src/minivhd_internal.h
index e805d26..cbf4142 100644
--- a/src/minivhd_internal.h
+++ b/src/minivhd_internal.h
@@ -68,4 +68,7 @@ void mvhd_buffer_to_header(MVHDSparseHeader* header, uint8_t* buffer);
 void mvhd_footer_to_buffer(MVHDFooter* footer, uint8_t* buffer);
 void mvhd_header_to_buffer(MVHDSparseHeader* header, uint8_t* buffer);
 void mvhd_generate_uuid(uint8_t *uuid);
+int mvhd_fixed_read(MVHDMeta* vhdm, int offset, int num_sectors, void* out_buff);
+int mvhd_sparse_read(MVHDMeta* vhdm, int offset, int num_sectors, void* out_buff);
+int mvhd_diff_read(MVHDMeta* vhdm, int offset, int num_sectors, void* out_buff);
 #endif
\ No newline at end of file
diff --git a/src/minivhd_manage.c b/src/minivhd_manage.c
index 6558589..6f78f4f 100644
--- a/src/minivhd_manage.c
+++ b/src/minivhd_manage.c
@@ -97,6 +97,20 @@ static void mvhd_calc_sparse_values(MVHDMeta* vhdm) {
     }
 }
 
+static void mvhd_assign_io_funcs(MVHDMeta* vhdm) {
+    switch (vhdm->footer.disk_type) {
+    case MVHD_TYPE_FIXED:
+        vhdm->read_sectors = mvhd_fixed_read;
+        break;
+    case MVHD_TYPE_DYNAMIC:
+        vhdm->read_sectors = mvhd_sparse_read;
+        break;
+    case MVHD_TYPE_DIFF:
+        vhdm->read_sectors = mvhd_diff_read;
+        break;
+    }
+}
+
 MVHDGeom mvhd_calculate_geometry(int size_mb, int* new_size) {
     MVHDGeom chs;
     uint32_t ts = ((uint64_t)size_mb * 1024 * 1024) / MVHD_SECTOR_SIZE;
@@ -172,6 +186,7 @@ MVHDMeta* mvhd_open(const char* path, int* err) {
         *err = MVHD_ERR_TYPE;
         goto cleanup_file;
     }
+    mvhd_assign_io_funcs(vhdm);
     /* If we've reached this point, we are good to go, so skip the cleanup steps */
     goto end;
 cleanup_file: