diff --git a/README.md b/README.md
index e7af1fe6..39733031 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,7 @@ CAD program, and create G-Code for Isolation routing.
 - completed the Minimum Distance Tool by adding the usage in Editors
 - made the Minimum Distance Tool more precise for the Excellon Editor since in the Excellon Editor the holes shape are represented as a cross line but in reality they should be evaluated as circles
 - small change in the UI layout for Check Rules Tool by adding a new rule (Check trace size)
+- changed a tooltip in Optimal Tool
 
 29.09.2019
 
diff --git a/flatcamTools/ToolOptimal.py b/flatcamTools/ToolOptimal.py
index 554d42f3..89513f38 100644
--- a/flatcamTools/ToolOptimal.py
+++ b/flatcamTools/ToolOptimal.py
@@ -51,7 +51,7 @@ class ToolOptimal(FlatCAMTool):
 
         self.gerber_object_label = QtWidgets.QLabel("<b>%s:</b>" % _("GERBER"))
         self.gerber_object_label.setToolTip(
-            "Gerber  to be mirrored."
+            "Gerber object for which to find the minimum distance between copper features."
         )
 
         self.title_res_label = QtWidgets.QLabel('<b>%s</b>' % _("Minimum distance between copper features"))