diff --git a/lbrynet/stream/assembler.py b/lbrynet/stream/assembler.py
index 356a8af76..6b325d248 100644
--- a/lbrynet/stream/assembler.py
+++ b/lbrynet/stream/assembler.py
@@ -88,7 +88,10 @@ class StreamAssembler:
         await self.blob_manager.blob_completed(self.sd_blob)
         with open(self.output_path, 'wb') as stream_handle:
             self.stream_handle = stream_handle
-            for blob_info in self.descriptor.blobs[:-1]:
+            for i, blob_info in enumerate(self.descriptor.blobs[:-1]):
+                if blob_info.blob_num != i:
+                    log.error("sd blob %s is invalid, cannot assemble stream", self.descriptor.sd_hash)
+                    return
                 while not stream_handle.closed:
                     try:
                         blob = await self.get_blob(blob_info.blob_hash, blob_info.length)
diff --git a/lbrynet/stream/descriptor.py b/lbrynet/stream/descriptor.py
index 453852d28..103f42e18 100644
--- a/lbrynet/stream/descriptor.py
+++ b/lbrynet/stream/descriptor.py
@@ -102,6 +102,8 @@ class StreamDescriptor:
             raise InvalidStreamDescriptorError("Contains zero-length data blob")
         if 'blob_hash' in decoded['blobs'][-1]:
             raise InvalidStreamDescriptorError("Stream terminator blob should not have a hash")
+        if any([i != blob_info['blob_num'] for i, blob_info in enumerate(decoded['blobs'])]):
+            raise InvalidStreamDescriptorError("Stream contains out of order or skipped blobs")
         descriptor = cls(
             loop, blob_dir,
             binascii.unhexlify(decoded['stream_name']).decode(),
diff --git a/tests/unit/stream/test_stream_descriptor.py b/tests/unit/stream/test_stream_descriptor.py
new file mode 100644
index 000000000..f634e9972
--- /dev/null
+++ b/tests/unit/stream/test_stream_descriptor.py
@@ -0,0 +1,77 @@
+import os
+import asyncio
+import tempfile
+import shutil
+import json
+
+from torba.testcase import AsyncioTestCase
+from lbrynet.conf import Config
+from lbrynet.error import InvalidStreamDescriptorError
+from lbrynet.extras.daemon.storage import SQLiteStorage
+from lbrynet.blob.blob_manager import BlobFileManager
+from lbrynet.stream.descriptor import StreamDescriptor
+
+
+class TestStreamDescriptor(AsyncioTestCase):
+    async def asyncSetUp(self):
+        self.loop = asyncio.get_event_loop()
+        self.key = b'deadbeef' * 4
+        self.cleartext = os.urandom(20000000)
+        self.tmp_dir = tempfile.mkdtemp()
+        self.addCleanup(lambda: shutil.rmtree(self.tmp_dir))
+        self.storage = SQLiteStorage(Config(), ":memory:")
+        await self.storage.open()
+        self.blob_manager = BlobFileManager(self.loop, self.tmp_dir, self.storage)
+
+        self.file_path = os.path.join(self.tmp_dir, "test_file")
+        with open(self.file_path, 'wb') as f:
+            f.write(self.cleartext)
+
+        self.descriptor = await StreamDescriptor.create_stream(self.loop, self.tmp_dir, self.file_path, key=self.key)
+        self.sd_hash = self.descriptor.calculate_sd_hash()
+        self.sd_dict = json.loads(self.descriptor.as_json())
+
+    def _write_sd(self):
+        with open(os.path.join(self.tmp_dir, self.sd_hash), 'wb') as f:
+            f.write(json.dumps(self.sd_dict, sort_keys=True).encode())
+
+    async def _test_invalid_sd(self):
+        self._write_sd()
+        with self.assertRaises(InvalidStreamDescriptorError):
+            await self.blob_manager.get_stream_descriptor(self.sd_hash)
+
+    async def test_load_sd_blob(self):
+        self._write_sd()
+        descriptor = await self.blob_manager.get_stream_descriptor(self.sd_hash)
+        self.assertEqual(descriptor.calculate_sd_hash(), self.sd_hash)
+
+    async def test_missing_terminator(self):
+        self.sd_dict['blobs'].pop()
+        await self._test_invalid_sd()
+
+    async def test_terminator_not_at_end(self):
+        terminator = self.sd_dict['blobs'].pop()
+        self.sd_dict['blobs'] = [terminator] + self.sd_dict['blobs']
+        await self._test_invalid_sd()
+
+    async def test_terminator_has_blob_hash(self):
+        self.sd_dict['blobs'][-1]['blob_hash'] = '1' * 96
+        await self._test_invalid_sd()
+
+    async def test_blob_order(self):
+        terminator = self.sd_dict['blobs'].pop()
+        self.sd_dict['blobs'].reverse()
+        self.sd_dict['blobs'].append(terminator)
+        await self._test_invalid_sd()
+
+    async def test_skip_blobs(self):
+        self.sd_dict['blobs'][-2]['blob_num'] = self.sd_dict['blobs'][-2]['blob_num'] + 1
+        await self._test_invalid_sd()
+
+    async def test_invalid_stream_hash(self):
+        self.sd_dict['blobs'][-2]['blob_hash'] = '1' * 96
+        await self._test_invalid_sd()
+
+    async def test_zero_length_blob(self):
+        self.sd_dict['blobs'][-2]['length'] = 0
+        await self._test_invalid_sd()