diff --git a/taskcluster/taskgraph/docker.py b/taskcluster/taskgraph/docker.py
index 22480b864357..9511afb0c958 100644
--- a/taskcluster/taskgraph/docker.py
+++ b/taskcluster/taskgraph/docker.py
@@ -93,29 +93,6 @@ def build_image(name, tag, args=None):
         print('*' * 50)
 
 
-# The zstandard library doesn't expose a file-like interface for its
-# decompressor, but an iterator. Support for a file-like interface is due in
-# next release. In the meanwhile, we use this proxy class to turn the iterator
-# into a file-like.
-class IteratorReader(object):
-    def __init__(self, iterator):
-        self._iterator = iterator
-        self._buf = b''
-
-    def read(self, size):
-        result = b''
-        while len(result) < size:
-            wanted = min(size - len(result), len(self._buf))
-            if not self._buf:
-                try:
-                    self._buf = memoryview(next(self._iterator))
-                except StopIteration:
-                    break
-            result += self._buf[:wanted].tobytes()
-            self._buf = self._buf[wanted:]
-        return result
-
-
 def load_image(url, imageName=None, imageTag=None):
     """
     Load docker image from URL as imageName:tag, if no imageName or tag is given
@@ -143,58 +120,63 @@ def load_image(url, imageName=None, imageTag=None):
         # get_session() gets us a requests.Session set to retry several times.
         req = get_session().get(url, stream=True)
         req.raise_for_status()
-        decompressed_reader = IteratorReader(zstd.ZstdDecompressor().read_from(req.raw))
-        tarin = tarfile.open(
-            mode='r|',
-            fileobj=decompressed_reader,
-            bufsize=zstd.DECOMPRESSION_RECOMMENDED_OUTPUT_SIZE)
 
-        # Stream through each member of the downloaded tar file individually.
-        for member in tarin:
-            # Non-file members only need a tar header. Emit one.
-            if not member.isfile():
+        with zstd.ZstdDecompressor().stream_reader(req.raw) as ifh:
+
+            tarin = tarfile.open(
+                mode='r|',
+                fileobj=ifh,
+                bufsize=zstd.DECOMPRESSION_RECOMMENDED_OUTPUT_SIZE)
+
+            # Stream through each member of the downloaded tar file individually.
+            for member in tarin:
+                # Non-file members only need a tar header. Emit one.
+                if not member.isfile():
+                    yield member.tobuf(tarfile.GNU_FORMAT)
+                    continue
+
+                # Open stream reader for the member
+                reader = tarin.extractfile(member)
+
+                # If member is `repositories`, we parse and possibly rewrite the
+                # image tags.
+                if member.name == 'repositories':
+                    # Read and parse repositories
+                    repos = json.loads(reader.read())
+                    reader.close()
+
+                    # If there is more than one image or tag, we can't handle it
+                    # here.
+                    if len(repos.keys()) > 1:
+                        raise Exception('file contains more than one image')
+                    info['image'] = image = repos.keys()[0]
+                    if len(repos[image].keys()) > 1:
+                        raise Exception('file contains more than one tag')
+                    info['tag'] = tag = repos[image].keys()[0]
+                    info['layer'] = layer = repos[image][tag]
+
+                    # Rewrite the repositories file
+                    data = json.dumps({imageName or image: {imageTag or tag: layer}})
+                    reader = BytesIO(data)
+                    member.size = len(data)
+
+                # Emit the tar header for this member.
                 yield member.tobuf(tarfile.GNU_FORMAT)
-                continue
+                # Then emit its content.
+                remaining = member.size
+                while remaining:
+                    length = min(remaining,
+                                 zstd.DECOMPRESSION_RECOMMENDED_OUTPUT_SIZE)
+                    buf = reader.read(length)
+                    remaining -= len(buf)
+                    yield buf
+                # Pad to fill a 512 bytes block, per tar format.
+                remainder = member.size % 512
+                if remainder:
+                    yield '\0' * (512 - remainder)
 
-            # Open stream reader for the member
-            reader = tarin.extractfile(member)
-
-            # If member is `repositories`, we parse and possibly rewrite the image tags
-            if member.name == 'repositories':
-                # Read and parse repositories
-                repos = json.loads(reader.read())
                 reader.close()
 
-                # If there is more than one image or tag, we can't handle it here
-                if len(repos.keys()) > 1:
-                    raise Exception('file contains more than one image')
-                info['image'] = image = repos.keys()[0]
-                if len(repos[image].keys()) > 1:
-                    raise Exception('file contains more than one tag')
-                info['tag'] = tag = repos[image].keys()[0]
-                info['layer'] = layer = repos[image][tag]
-
-                # Rewrite the repositories file
-                data = json.dumps({imageName or image: {imageTag or tag: layer}})
-                reader = BytesIO(data)
-                member.size = len(data)
-
-            # Emit the tar header for this member.
-            yield member.tobuf(tarfile.GNU_FORMAT)
-            # Then emit its content.
-            remaining = member.size
-            while remaining:
-                length = min(remaining, zstd.DECOMPRESSION_RECOMMENDED_OUTPUT_SIZE)
-                buf = reader.read(length)
-                remaining -= len(buf)
-                yield buf
-            # Pad to fill a 512 bytes block, per tar format.
-            remainder = member.size % 512
-            if remainder:
-                yield '\0' * (512 - remainder)
-
-            reader.close()
-
     docker.post_to_docker(download_and_modify_image(), '/images/load', quiet=0)
 
     # Check that we found a repositories file