diff --git a/pypesto/visualize/parameters.py b/pypesto/visualize/parameters.py
index 61269e3fc..baee313e0 100644
--- a/pypesto/visualize/parameters.py
+++ b/pypesto/visualize/parameters.py
@@ -464,7 +464,7 @@ def handle_inputs(
 
     # If all the scales are the same, put it in the x_axis_label
     if len({x_scale for _, x_scale in x_labels}) == 1:
-        x_axis_label = "Parameter value (" + x_labels[0][1] + ")"
+        x_axis_label = "Parameter value (" + x_labels[0][1].decode('utf-8') + ")"
         x_labels = [x_name for x_name, _ in x_labels]
     else:
         x_axis_label = "Parameter value"