diff --git a/tools.py b/tools.py
index 792271dfe4e42edb928abba6c5ef3868978b32ab..040c00561df44ec9e6cd36a330558b70eb4361d2 100644
--- a/tools.py
+++ b/tools.py
@@ -126,6 +126,9 @@ class Main:
             if len(coord) > 1 and dist_factor is not None:
                 coord, fit_error = dark_ions(img, coord, dist_factor)
                 self.fit_avg.update_value(fit_error)
+
+            else:
+                fit_error = -1
         else:
             roundness = 0
             fit_error = -1