diff --git a/glue_jupyter/common/toolbar_vuetify.py b/glue_jupyter/common/toolbar_vuetify.py
index 9a08cffd..10423081 100644
--- a/glue_jupyter/common/toolbar_vuetify.py
+++ b/glue_jupyter/common/toolbar_vuetify.py
@@ -70,14 +70,17 @@ def _on_change_active_tool(self, change):
     def add_tool(self, tool):
         self.tools[tool.tool_id] = tool
         # TODO: we should ideally just incorporate this check into icon_path directly.
+        ext = os.path.splitext(tool.icon)[1][1:] or "svg"
         if os.path.exists(tool.icon):
             path = tool.icon
         else:
-            path = icon_path(tool.icon, icon_format='svg')
+            path = icon_path(tool.icon, icon_format=ext)
+
+        format = "svg+xml" if ext == "svg" else ext
         self.tools_data = {
             **self.tools_data,
             tool.tool_id: {
                 'tooltip': tool.tool_tip,
-                'img': read_icon(path, 'svg+xml')
+                'img': read_icon(path, format)
             }
         }