diff --git a/src/fourier/euclidian.hpp b/src/fourier/euclidian.hpp
index 1fbd480..56d6964 100644
--- a/src/fourier/euclidian.hpp
+++ b/src/fourier/euclidian.hpp
@@ -195,7 +195,7 @@ namespace CosmoTool
 	{
 	  for (long p = 0; p < plane_size; p++)
 	    {
-	      long idx = q0+N0*p;
+	      long idx = q0+dims[0]*p;
 	      assert(idx < this->size());
 	      result += 2*(conj(d1[idx]) * d2[idx]).real();
 	    }