diff --git a/requirements-swh-with-content.txt b/requirements-swh-with-content.txt
new file mode 100644
--- /dev/null
+++ b/requirements-swh-with-content.txt
@@ -0,0 +1 @@
+swh.objstorage
diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -2,5 +2,4 @@
 swh.core[http] >= 2
 swh.journal >= 0.9
 swh.model >= 4.3
-swh.objstorage
 swh.storage
diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -51,7 +51,10 @@
         dataset=swh.dataset.cli
     """,
     setup_requires=["setuptools-scm"],
-    extras_require={"testing": parse_requirements("test")},
+    extras_require={
+        "testing": parse_requirements("test"),
+        "with-content": parse_requirements("swh-with-content"),
+    },
     use_scm_version=True,
     include_package_data=True,
     classifiers=[
diff --git a/swh/dataset/exporters/orc.py b/swh/dataset/exporters/orc.py
--- a/swh/dataset/exporters/orc.py
+++ b/swh/dataset/exporters/orc.py
@@ -8,7 +8,7 @@
 import logging
 import math
 from types import TracebackType
-from typing import Any, Optional, Tuple, Type, cast
+from typing import Any, Callable, Optional, Tuple, Type, cast
 
 from pkg_resources import get_distribution
 from pyorc import (
@@ -30,8 +30,18 @@
 from swh.dataset.utils import remove_pull_requests
 from swh.model.hashutil import hash_to_hex
 from swh.model.model import TimestampWithTimezone
-from swh.objstorage.factory import get_objstorage
-from swh.objstorage.objstorage import ID_HASH_ALGO, ObjNotFoundError
+
+ObjNotFoundError: Type[Exception]
+get_objstorage: Optional[Callable]
+ID_HASH_ALGO: str
+try:
+    from swh.objstorage.factory import get_objstorage
+    from swh.objstorage.objstorage import ID_HASH_ALGO, ObjNotFoundError
+except ImportError:
+    get_objstorage = None
+    ID_HASH_ALGO = ""
+    ObjNotFoundError = Exception  # helps keep mypy happy
+
 
 ORC_TYPE_MAP = {
     "string": String,
@@ -138,7 +148,15 @@
         self.with_data = config.get("with_data", False)
         self.objstorage = None
         if self.with_data:
-            assert "objstorage" in config
+            if get_objstorage is None:
+                raise EnvironmentError(
+                    "The swh-objstorage dependency package must be installed "
+                    "when 'with_data' is set. Please install 'swh.dataset[with-content]'"
+                )
+            if "objstorage" not in config:
+                raise ValueError(
+                    "The 'objstorage' configuration entry is mandatory when 'with_data' is set."
+                )
             self.objstorage = get_objstorage(**config["objstorage"])
         self._reset()