diff --git a/mappymatch/constructs/trace.py b/mappymatch/constructs/trace.py
index a09d30f..f71f863 100644
--- a/mappymatch/constructs/trace.py
+++ b/mappymatch/constructs/trace.py
@@ -53,7 +53,7 @@ def __len__(self):
     def __str__(self):
         output_lines = [
             "Mappymatch Trace object",
-            f'coords: {self.coords if hasattr(self, "coords") else None}',
+            f"coords: {self.coords if hasattr(self, 'coords') else None}",
             f"frame: {self._frame}",
         ]
         return "\n".join(output_lines)