diff --git a/Troubled_Cell_Detector.py b/Troubled_Cell_Detector.py
index af30a1f302c9a37e716665d82f38365122b4f72c..24e7ec19288ceb0e32fd93b00580378ba2c27bb3 100644
--- a/Troubled_Cell_Detector.py
+++ b/Troubled_Cell_Detector.py
@@ -240,8 +240,8 @@ class WaveletDetector(TroubledCellDetector):
         output_matrix = []
         for i in range(self._mesh.num_grid_cells):
             new_entry = 0.5*(
-                    projection[:, i] @ self._wavelet_projection_left
-                    + projection[:, i+1] @ self._wavelet_projection_right)
+                    projection[:, i+1] @ self._wavelet_projection_left
+                    + projection[:, i+2] @ self._wavelet_projection_right)
             output_matrix.append(new_entry)
         return np.transpose(np.array(output_matrix))