diff --git a/src/octoprint/plugins/pluginmanager/__init__.py b/src/octoprint/plugins/pluginmanager/__init__.py
index 05ab3784..58b662bb 100644
--- a/src/octoprint/plugins/pluginmanager/__init__.py
+++ b/src/octoprint/plugins/pluginmanager/__init__.py
@@ -121,7 +121,7 @@ class PluginManagerPlugin(octoprint.plugin.SimpleApiPlugin,
 		upload_path = flask.request.values[input_upload_path]
 		upload_name = flask.request.values[input_upload_name]
 
-		exts = filter(lambda x: upload_name.endswith(x), (".zip", ".tar.gz", ".tgz", ".tar"))
+		exts = filter(lambda x: upload_name.lower().endswith(x), (".zip", ".tar.gz", ".tgz", ".tar"))
 		if not len(exts):
 			return flask.make_response("File doesn't have a valid extension for a plugin archive", 400)
 
diff --git a/src/octoprint/server/api/languages.py b/src/octoprint/server/api/languages.py
index ef35d99d..1d9c7e9c 100644
--- a/src/octoprint/server/api/languages.py
+++ b/src/octoprint/server/api/languages.py
@@ -97,7 +97,7 @@ def uploadLanguagePack():
 	upload_name = request.values[input_upload_name]
 	upload_path = request.values[input_upload_path]
 
-	exts = filter(lambda x: upload_name.endswith(x), (".zip", ".tar.gz", ".tgz", ".tar"))
+	exts = filter(lambda x: upload_name.lower().endswith(x), (".zip", ".tar.gz", ".tgz", ".tar"))
 	if not len(exts):
 		return make_response("File doesn't have a valid extension for a plugin archive", 400)