diff --git a/R/measurement_utils.R b/R/measurement_utils.R
index 6d5ac76..485e424 100644
--- a/R/measurement_utils.R
+++ b/R/measurement_utils.R
@@ -1,7 +1,7 @@
 #' @export
-plot.osem_measurements = function (x, ...) {
+plot.osem_measurements = function (x, ..., mar = c(2,4,1,1)) {
   oldpar = par()
-  par(mar = c(2,4,1,1))
+  par(mar = mar)
   plot(value~createdAt, x, col = factor(x$sensorId), xlab = NA, ylab = x$unit[1], ...)
   par(mar = oldpar$mar)
   invisible(x)
@@ -10,6 +10,7 @@ plot.osem_measurements = function (x, ...) {
 #' @export
 print.osem_measurements = function (x, ...) {
   print.data.frame(x, ...)
+  invisible(x)
 }
 
 #' Converts a foreign object to an osem_measurements data.frame.