diff --git a/swh/loader/npm/client.py b/swh/loader/npm/client.py
--- a/swh/loader/npm/client.py
+++ b/swh/loader/npm/client.py
@@ -204,7 +204,8 @@
         with open(package_json_path, 'rb') as package_json_file:
             package_json_bytes = package_json_file.read()
             file_encoding = chardet.detect(package_json_bytes)['encoding']
-            package_json = json.loads(package_json_bytes.decode(file_encoding))
+            package_json = json.loads(package_json_bytes.decode(file_encoding,
+                                                                'replace'))
 
         # extract author from package.json
         author = extract_npm_package_author(package_json)