diff --git a/src/calng/kernels/peakfinder9_gpu.cu b/src/calng/kernels/peakfinder9_gpu.cu
index 29a538438c8e24e2fde1c70d719702054d468c1e..fda8259ea46d47e157d0481621540662dd412b77 100644
--- a/src/calng/kernels/peakfinder9_gpu.cu
+++ b/src/calng/kernels/peakfinder9_gpu.cu
@@ -161,7 +161,7 @@ extern "C" __global__ void pf9(const unsigned short num_frames,
 		float peak_weighted_fs_nom = 0;
 		// expand peak in rings
 		const float peak_pixel_threshold = mean + min_snr_peak_pixels * sigma;
-		for (unsigned short layer=1; layer<=window_radius; ++layer) {
+		for (unsigned short layer=0; layer<=window_radius; ++layer) {
 			unsigned num_peak_pixels_before = num_peak_pixels;
 			masked_frame.fun_ring(ss_index, fs_index, layer, [&] (unsigned short i, unsigned short j, float val) {
 				if (val > peak_pixel_threshold) {