diff --git a/README.md b/README.md
index 8c41060a..85aeedf7 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,7 @@ CAD program, and create G-Code for Isolation routing.
 
 - fixed a small bug in BETA status change
 - updated the About FlatCAM window
+- reverted change in tool dia being able to take only positive values in Gerber Object UI
 
 18.10.2019
 
diff --git a/flatcamGUI/ObjectUI.py b/flatcamGUI/ObjectUI.py
index d66df03b..318d10c6 100644
--- a/flatcamGUI/ObjectUI.py
+++ b/flatcamGUI/ObjectUI.py
@@ -342,7 +342,7 @@ class GerberObjectUI(ObjectUI):
         )
         tdlabel.setMinimumWidth(90)
         self.iso_tool_dia_entry = FCDoubleSpinner()
-        self.iso_tool_dia_entry.set_range(0, 9999.9999)
+        self.iso_tool_dia_entry.set_range(-9999.9999, 9999.9999)
         self.iso_tool_dia_entry.set_precision(self.decimals)
         self.iso_tool_dia_entry.setSingleStep(0.1)