diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,4 +1,4 @@
-swh.core >= 0.0.54
+swh.core >= 0.0.56
 swh.model >= 0.0.27
 swh.objstorage >= 0.0.17
 swh.scheduler >= 0.0.14
diff --git a/swh/storage/api/client.py b/swh/storage/api/client.py
--- a/swh/storage/api/client.py
+++ b/swh/storage/api/client.py
@@ -12,9 +12,7 @@
 
 class RemoteStorage(SWHRemoteAPI):
     """Proxy to a remote storage API"""
-    def __init__(self, url, timeout=None):
-        super().__init__(
-            api_exception=StorageAPIError, url=url, timeout=timeout)
+    api_exception = StorageAPIError
 
     def check_config(self, *, check_write):
         return self.post('check_config', {'check_write': check_write})
@@ -54,8 +52,8 @@
         return self.post('directory/missing', {'directories': directories})
 
     def directory_ls(self, directory, recursive=False):
-        return self.get('directory/ls', {'directory': directory,
-                                         'recursive': recursive})
+        return self.post('directory/ls', {'directory': directory,
+                                          'recursive': recursive})
 
     def revision_get(self, revisions):
         return self.post('revision', {'revisions': revisions})
diff --git a/swh/storage/api/server.py b/swh/storage/api/server.py
--- a/swh/storage/api/server.py
+++ b/swh/storage/api/server.py
@@ -4,7 +4,6 @@
 # See top-level LICENSE file for more information
 
 import os
-import json
 import logging
 
 from flask import request
@@ -112,11 +111,10 @@
         **decode_request(request)))
 
 
-@app.route('/directory/ls', methods=['GET'])
+@app.route('/directory/ls', methods=['POST'])
 def directory_ls():
-    dir = request.args['directory'].encode('utf-8', 'surrogateescape')
-    rec = json.loads(request.args.get('recursive', 'False').lower())
-    return encode_data(get_storage().directory_ls(dir, recursive=rec))
+    return encode_data(get_storage().directory_ls(
+        **decode_request(request)))
 
 
 @app.route('/revision/add', methods=['POST'])