diff --git a/CHANGELOG.md b/CHANGELOG.md
index 063c93d..df28c02 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+## 0.9.12 (2025-07-07)
+
+- Support an optional bodyId parameter when downloading environment.
+
 ## 0.9.11 (2025-07-04)
 
 - Re-generate graph client.
diff --git a/python/mujinwebstackclient/uriutils.py b/python/mujinwebstackclient/uriutils.py
index 53935bb..36130d9 100644
--- a/python/mujinwebstackclient/uriutils.py
+++ b/python/mujinwebstackclient/uriutils.py
@@ -86,7 +86,7 @@ def _Unquote(primaryKey):
     return _EnsureUnicode(unquote(primaryKey))
 
 
-def _Quote(primaryKey):
+def Quote(primaryKey):
     assert isinstance(primaryKey, six.text_type)
     return _EnsureUTF8(quote(_EnsureUTF8(primaryKey), safe=''))
 
@@ -497,12 +497,12 @@ def _InitFromPartType(self, partType):
                 self._fragment = _EnsureUnicode(partTypeSegments[1])
         else:
             basePartType = partType
-        self._primaryKey = _Quote(basePartType + self._suffix)
+        self._primaryKey = Quote(basePartType + self._suffix)
 
     def _InitFromFilename(self, filename):
         if self._mujinPath and filename.startswith(self._mujinPath):
             filename = filename[len(self._mujinPath) :]
-        self._primaryKey = _Quote(filename)
+        self._primaryKey = Quote(filename)
 
     @property
     def scheme(self):
@@ -598,7 +598,7 @@ def environmentId(self):
 
     @environmentId.setter
     def environmentId(self, value):
-        self._primaryKey = _Quote(_EnsureUnicode(value) + self._suffix)
+        self._primaryKey = Quote(_EnsureUnicode(value) + self._suffix)
 
     @property
     def filename(self):
diff --git a/python/mujinwebstackclient/version.py b/python/mujinwebstackclient/version.py
index 6f299a5..0c9165f 100644
--- a/python/mujinwebstackclient/version.py
+++ b/python/mujinwebstackclient/version.py
@@ -1,3 +1,3 @@
-__version__ = '0.9.11'
+__version__ = '0.9.12'
 
 # Do not forget to update CHANGELOG.md
diff --git a/python/mujinwebstackclient/webstackclient.py b/python/mujinwebstackclient/webstackclient.py
index 86a8fc6..ee3d104 100644
--- a/python/mujinwebstackclient/webstackclient.py
+++ b/python/mujinwebstackclient/webstackclient.py
@@ -774,6 +774,7 @@ def DownloadFile(self, filename, ifmodifiedsince=None, resolveReferences=False,
         params = {
             'resolveReferences': 'true' if resolveReferences else 'false',
         }
+        filename = uriutils.Quote(filename) # quote '#bodyId' into '%23bodyId'
         response = self._webclient.Request('GET', '/u/%s/%s' % (self.controllerusername, filename), params=params, headers=headers, stream=True, timeout=timeout)
         if ifmodifiedsince and response.status_code == 304:
             return response