diff --git a/rotation.cpp b/rotation.cpp
index 56fa935..bcdc155 100644
--- a/rotation.cpp
+++ b/rotation.cpp
@@ -143,10 +143,11 @@ DPoint get_mapped_point(Image const& src, Point const& p, double const rotation)
 
 void round_if_very_small(double& d)
 {
-  if (abs(d) < 1.0e-10)
+  double const sigma = 1.0e-10;
+  if (abs(d) < sigma)
     d = 0.0;
 
-  if (abs(d - 1) < 1.0e-10)
+  if (abs(d - 1) < sigma)
     d = 1.0;
 }
 
@@ -513,7 +514,11 @@ Image* rotate(Image const& src, double angle)
   DPoint src_delta_x = get_mapped_point(*rotated, Point(src.width, 0), -rotation);
   DPoint src_delta_y = get_mapped_point(*rotated, Point(0, src.height), -rotation);
   src_delta_x -= src_origin;
+  round_if_very_small(src_delta_x.x);
+  round_if_very_small(src_delta_x.y);
   src_delta_y -= src_origin;
+  round_if_very_small(src_delta_y.x);
+  round_if_very_small(src_delta_y.y);
 
   // Quantized position on a grid
   int const q_pos_pow = 10;