diff --git a/sphinx_asdf/asdf2rst.py b/sphinx_asdf/asdf2rst.py
index 71ae1d6..6513493 100644
--- a/sphinx_asdf/asdf2rst.py
+++ b/sphinx_asdf/asdf2rst.py
@@ -46,6 +46,50 @@ def run(self):
             return []
 
 
+def _block_to_string(block):
+    if hasattr(block, "header"):
+        header = block.header
+        data = block.data
+    else:
+        data = block.data
+        header = {
+            "flags": block._flags,
+            "allocated_size": block._allocated,
+            "used_size": block._size,
+            "data_size": block._data_size,
+            "compression": block.input_compression,
+        }
+    if header["flags"] & BLOCK_FLAG_STREAMED:
+        header["allocated"] = header["used_size"] = header["data_size"] = 0
+
+    # convert data to hex representation
+    data = codecs.encode(data.tobytes(), "hex")
+    if len(data) > 40:
+        data = data[:40] + b"..."
+
+    lines = []
+
+    # convert header to string, add to lines
+    human_flags = []
+    for key, val in FLAGS.items():
+        if header["flags"] & key:
+            human_flags.append(val)
+    if len(human_flags):
+        lines.append("    flags: {}".format(" | ".join(human_flags)))
+    if header["compression"] and header["compression"] != b"\0\0\0\0":
+        lines.append(f"    compression: {header['compression']}")
+    lines.append(f"    allocated_size: {header['allocated_size']}")
+    lines.append(f"    used_size: {header['used_size']}")
+    lines.append(f"    data_size: {header['data_size']}")
+
+    # add data as string to lines
+    lines.append(f"    data: {data}")
+
+    # add lines to code block
+    code = "\n".join(lines)
+    return code
+
+
 class AsdfDirective(Directive):
     required_arguments = 1
     optional_arguments = 1
@@ -91,52 +135,40 @@ def run(self):
 
             if show_bocks:
                 with asdf.open(filename, **kwargs) as ff:
-                    for i, block in enumerate(ff._blocks.internal_blocks):
-                        data = codecs.encode(block.data.tobytes(), "hex")
-                        if len(data) > 40:
-                            data = data[:40] + b"..."
-                        allocated = block._allocated
-                        size = block._size
-                        data_size = block._data_size
-                        flags = block._flags
-
-                        if flags & BLOCK_FLAG_STREAMED:
-                            allocated = size = data_size = 0
-
-                        lines = []
-                        lines.append(f"BLOCK {i}:")
-
-                        human_flags = []
-                        for key, val in FLAGS.items():
-                            if flags & key:
-                                human_flags.append(val)
-                        if len(human_flags):
-                            lines.append("    flags: {}".format(" | ".join(human_flags)))
-                        if block.input_compression:
-                            lines.append(f"    compression: {block.input_compression}")
-                        lines.append(f"    allocated_size: {allocated}")
-                        lines.append(f"    used_size: {size}")
-                        lines.append(f"    data_size: {data_size}")
-                        lines.append(f"    data: {data}")
-
-                        code = "\n".join(lines)
-                        code += "\n"
+                    if hasattr(ff._blocks, "internal_blocks"):
+                        blocks = list(ff._blocks.internal_blocks)
+                    else:
+                        blocks = ff._blocks.blocks
 
+                    for i, block in enumerate(blocks):
+                        code = "\n".join([f"BLOCK {i}:", _block_to_string(block), ""])
                         literal = nodes.literal_block(code, code)
                         literal["language"] = "yaml"
                         set_source_info(self, literal)
                         parts.append(literal)
 
-                    internal_blocks = list(ff._blocks.internal_blocks)
-                    if len(internal_blocks) and internal_blocks[-1].array_storage != "streamed":
-                        buff = io.BytesIO()
-                        ff._blocks.write_block_index(buff, ff)
-                        block_index = buff.getvalue().decode("utf-8")
-                        literal = nodes.literal_block(block_index, block_index)
-                        literal["language"] = "yaml"
-                        set_source_info(self, literal)
-                        parts.append(literal)
-
+                    # re-write out the block index
+                    if len(blocks):
+                        if hasattr(blocks[-1], "header"):
+                            streamed = blocks[-1].header["flags"] & BLOCK_FLAG_STREAMED
+                        else:
+                            streamed = blocks[-1].array_storage == "streamed"
+                        if not streamed:
+                            # write out the block index
+                            if hasattr(blocks[0], "header"):
+                                block_index_offset = asdf._block.io.find_block_index(ff._fd)
+                                buff = io.BytesIO()
+                                ff._fd.seek(block_index_offset)
+                                buff = io.BytesIO(ff._fd.read())
+                            else:
+                                buff = io.BytesIO()
+                                ff._blocks.write_block_index(buff, ff)
+
+                            block_index = buff.getvalue().decode("utf-8")
+                            literal = nodes.literal_block(block_index, block_index)
+                            literal["language"] = "yaml"
+                            set_source_info(self, literal)
+                            parts.append(literal)
         finally:
             os.chdir(cwd)