diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7111604..7c239c2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,7 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](https://semver.org/).
 
-## 3.0.3 - 2023-08-29
+## 3.0.4 - 2023-09-27
+
+### Fixed
+
+- Fixed host bug on v1 file thumbnail endpoint.
+- 
+- ## 3.0.3 - 2023-08-29
 
 ### Added
 
diff --git a/pyclowder/api/v1/files.py b/pyclowder/api/v1/files.py
index 39caef6..7ffd9ae 100644
--- a/pyclowder/api/v1/files.py
+++ b/pyclowder/api/v1/files.py
@@ -295,7 +295,7 @@ def upload_thumbnail(connector, client, fileid, thumbnail):
     """
 
     logger = logging.getLogger(__name__)
-    url = client.host + 'api/fileThumbnail?key=' + client.key
+    url = '%s/api/fileThumbnail?key=%s' % (client.host, client.key)
 
     # upload preview
     with open(thumbnail, 'rb') as inputfile:
@@ -303,10 +303,10 @@ def upload_thumbnail(connector, client, fileid, thumbnail):
     thumbnailid = result.json()['id']
     logger.debug("thumbnail id = [%s]", thumbnailid)
 
-    # associate uploaded preview with orginal file/dataset
+    # associate uploaded preview with original file/dataset
     if fileid:
         headers = {'Content-Type': 'application/json'}
-        url = client.host + 'api/files/' + fileid + '/thumbnails/' + thumbnailid + '?key=' + client.key
+        url = '%s/api/files/%s/thumbnails/%s?key=%s' % (client.host, fileid, thumbnailid, client.key)
         connector.post(url, headers=headers, data=json.dumps({}), verify=connector.ssl_verify if connector else True)
 
     return thumbnailid
diff --git a/setup.py b/setup.py
index e0a6af3..31b0ad6 100644
--- a/setup.py
+++ b/setup.py
@@ -8,7 +8,7 @@
 
 setup(
     name='pyclowder',
-    version='3.0.3',
+    version='3.0.4',
     description='Python SDK for the Clowder Data Management System',
     long_description=long_description,