diff --git a/engine/regions.go b/engine/regions.go
index 47ea8d57f..ccd536698 100644
--- a/engine/regions.go
+++ b/engine/regions.go
@@ -99,7 +99,7 @@ func (r *Regions) HostList() []byte {
 
 func DefRegionCell(id int, x, y, z int) {
 	defRegionId(id)
-	index := data.Index(Mesh().Size(), z, y, x)
+	index := data.Index(Mesh().Size(), x, y, z)
 	regions.gpuCache.Set(index, byte(id))
 }
 
diff --git a/mag/demagkernel.go b/mag/demagkernel.go
index f61ab6ded..8a86a8018 100644
--- a/mag/demagkernel.go
+++ b/mag/demagkernel.go
@@ -318,7 +318,7 @@ func CalcDemagKernel(inputSize, pbc [3]int, cellsize [3]float64, accuracy float6
 	return kernel
 }
 
-// integration ranges for kernel
+// integration ranges for kernel. size=kernelsize, so padded for no PBC, not padded for PBC
 func kernelRanges(size, pbc [3]int) (r1, r2 [3]int) {
 	for c := 0; c < 3; c++ {
 		if pbc[c] == 0 {