diff --git a/src/model/Stroke.cpp b/src/model/Stroke.cpp
index 2cf65de6..66de0157 100644
--- a/src/model/Stroke.cpp
+++ b/src/model/Stroke.cpp
@@ -156,6 +156,7 @@ void Stroke::setLastPoint(const Point& p)
 	if (!this->points.empty())
 	{
 		this->points.back() = p;
+		this->sizeCalculated = false;
 	}
 }