diff --git a/jmetal/lab/visualization/posterior.py b/jmetal/lab/visualization/posterior.py
index f28827ee..02518b31 100644
--- a/jmetal/lab/visualization/posterior.py
+++ b/jmetal/lab/visualization/posterior.py
@@ -96,6 +96,6 @@ def transform(p):
 
     if filename:
         plt.savefig(filename, bbox_inches="tight")
-        logger.info("Figure {filename} saved to file")
+        logger.info(f"Figure {filename} saved to file")
 
     plt.show()