diff --git a/src/mode/ModeRotate.cpp b/src/mode/ModeRotate.cpp
index 90c2b31..fc26983 100644
--- a/src/mode/ModeRotate.cpp
+++ b/src/mode/ModeRotate.cpp
@@ -19,6 +19,8 @@ SModeResult CModeRotate::update(Vector2D pos) {
 
     // normalize
     double size = end.size();
+    if (size == 0) size = 1; // do not divide by 0
+
     end.x /= size;
     end.y /= size;