diff --git a/src/Mod/Mesh/App/Core/Approximation.cpp b/src/Mod/Mesh/App/Core/Approximation.cpp
index c99a59746..d01e4833d 100644
--- a/src/Mod/Mesh/App/Core/Approximation.cpp
+++ b/src/Mod/Mesh/App/Core/Approximation.cpp
@@ -255,6 +255,9 @@ float PlaneFit::Fit()
 
     if (nSize > 3)
         sigma = sqrt(sigma/(nSize-3));
+    else
+        sigma = 0;
+
     _fLastResult = sigma;
     return _fLastResult;
 }