diff --git a/basetheme_bootstrap/templatetags/sstatic.py b/basetheme_bootstrap/templatetags/sstatic.py
index 3c364b1546faa6d8fc092c34dd688d85418037e3..b730fe50737b4fda72589b533d794833066ec54c 100644
--- a/basetheme_bootstrap/templatetags/sstatic.py
+++ b/basetheme_bootstrap/templatetags/sstatic.py
@@ -22,7 +22,7 @@ def sstatic(context, path):
 
 
 def get_absolut_url(request, relative_url):
-    return f"{request.scheme}://{request.get_host()}{relative_url}"
+    return "%s://%s%s" % (request.scheme, request.get_host(), relative_url)
 
 
 def compute_url_for_path(path):