diff --git a/graphviz2drawio/mx/Node.py b/graphviz2drawio/mx/Node.py
index f3bc5a7..a259304 100644
--- a/graphviz2drawio/mx/Node.py
+++ b/graphviz2drawio/mx/Node.py
@@ -16,7 +16,7 @@ def text_to_mx_value(self):
         last_text = len(self.texts) - 1
         for i, t in enumerate(self.texts):
             style = t.get_mx_style()
-            value += "<p style='" + style + "'>" + t.text + "</p>"
+            value += f"<p style='{style}'>{t.text}</p>"
             if i != last_text:
                 value += "<hr size='1'/>"
         return value
diff --git a/test/test_graphs.py b/test/test_graphs.py
index 7f45738..f56e0db 100644
--- a/test/test_graphs.py
+++ b/test/test_graphs.py
@@ -20,8 +20,8 @@ def check_style(e, check):
 
 def check_value(e, check):
     value = e.attrib["value"]
-    match = re.match(r"<p.*>%s</p>" % check, html.unescape(value))
-    assert match, "no match found for %s" % value
+    match = re.match(f"<p.*>{check}</p>", html.unescape(value))
+    assert match, f"no match found for {value}"
 
 
 def check_edge(edge, source, target):