diff --git a/tools/make-ptraccel-graphs.sh b/tools/make-ptraccel-graphs.sh
index 2e6c73afb..a98d79c7c 100755
--- a/tools/make-ptraccel-graphs.sh
+++ b/tools/make-ptraccel-graphs.sh
@@ -76,13 +76,13 @@ done
 $gnuplot <<EOF
 set terminal svg enhanced background rgb 'white'
 set output "$outfile.svg"
-set xlabel "delta (units)"
+set xlabel "delta (units/ms)"
 set ylabel "accel factor"
 set style data lines
 set yrange [0:5]
 set xrange [0:20]
 speeds="$speeds"
 fname(s)=sprintf("$outfile-%s.gnuplot", s)
-plot for [s in speeds] fname(s) using 1:2 title s, \
+plot for [s in speeds] fname(s) using 4:2 title s, \
 
 EOF
diff --git a/tools/ptraccel-debug.c b/tools/ptraccel-debug.c
index fbb067551..150a3b3b9 100644
--- a/tools/ptraccel-debug.c
+++ b/tools/ptraccel-debug.c
@@ -161,11 +161,12 @@ print_accel_func(struct motion_filter *filter,
 	printf("# set style data lines\n");
 	printf("# plot \"gnuplot.data\" using 1:2 title 'accel factor'\n");
 	printf("#\n");
-	printf("# data: velocity(mm/s) factor velocity(units/us)\n");
+	printf("# data: velocity(mm/s) factor velocity(units/us) velocity(units/ms)\n");
 	for (mmps = 0.0; mmps < 1000.0; mmps += 1) {
 		double units_per_us = mmps_to_upus(mmps, dpi);
+		double units_per_ms = units_per_us * 1000.0;
 		double result = profile(filter, NULL, units_per_us, 0 /* time */);
-		printf("%.8f\t%.4f\t%.8f\n", mmps, result, units_per_us);
+		printf("%.8f\t%.4f\t%.8f\t%.8f\n", mmps, result, units_per_us, units_per_ms);
 	}
 }