diff --git a/rotation.cpp b/rotation.cpp
index cc65513..fd7ef13 100644
--- a/rotation.cpp
+++ b/rotation.cpp
@@ -467,9 +467,10 @@ void rotate_pixel(Image const& src, Image& rotated,
 
   // Bilinear interpolation
   unsigned int src_index_1 = (floor(src_rotated_point.y) * src.width + floor(src_rotated_point.x)) * 3;
-  unsigned int src_index_2 = (floor(src_rotated_point.y) * src.width + ceil(src_rotated_point.x)) * 3;
-  unsigned int src_index_3 = (ceil(src_rotated_point.y) * src.width + floor(src_rotated_point.x)) * 3;
-  unsigned int src_index_4 = (ceil(src_rotated_point.y) * src.width + ceil(src_rotated_point.x)) * 3;
+  unsigned int src_index_2 = src_index_1 + 3;
+  unsigned int src_index_3 = src_index_1 + 3 * src.width;
+  unsigned int src_index_4 = src_index_3 + 3;
+
   if (src_index_1 >= src_limit || src_index_1 >= src_limit)
     return;