diff --git a/R/plot_slope.R b/R/plot_slope.R
index f36ab52..81bde37 100644
--- a/R/plot_slope.R
+++ b/R/plot_slope.R
@@ -3,15 +3,16 @@
 #' @inheritParams slope_raster
 #' @inheritParams plot_dz
 #' @inheritParams sequential_dist
+#' @param route_xyz An sf linestring with x, y and z coordinates,
+#'   representing a route or other linear object.
 #'
 #' @export
 #' @examples
 #' plot_slope(lisbon_route_3d)
-#' routes = lisbon_road_segment_3d
-#' plot_slope(routes)
-#' routes = lisbon_road_segment_3d
-plot_slope = function(routes,
-                      lonlat = sf::st_is_longlat(routes),
+#' route_xyz = lisbon_road_segment_3d
+#' plot_slope(route_xyz)
+plot_slope = function(route_xyz,
+                      lonlat = sf::st_is_longlat(route_xyz),
                       fill = TRUE,
                       horiz = FALSE,
                       p = colorspace::diverging_hcl,
@@ -23,7 +24,7 @@ plot_slope = function(routes,
                       title = "Slope colors (percentage gradient)",
                       s = 3:18,
                       ncol = 4) {
-  dz = distance_z(routes, lonlat = lonlat)
+  dz = distance_z(route_xyz, lonlat = lonlat)
   plot_dz(dz$d, dz$z, fill = fill)
 }
 #' Plot a digital elevation profile based on xyz data
@@ -45,8 +46,8 @@ plot_slope = function(routes,
 #' @param horiz Should the legend be horizontal (`FALSE` by default)
 #' @param ... Additional parameters to pass to legend
 #' @examples
-#' routes = lisbon_road_segment_3d
-#' m = sf::st_coordinates(routes)
+#' route_xyz = lisbon_road_segment_3d
+#' m = sf::st_coordinates(route_xyz)
 #' d = cumsum(sequential_dist(m, lonlat = FALSE))
 #' d = c(0, d)
 #' z = m[, 3]
@@ -88,8 +89,8 @@ plot_dz = function(d,
   }
 }
 
-distance_z = function(routes, lonlat) {
-  m = sf::st_coordinates(routes)
+distance_z = function(route_xyz, lonlat) {
+  m = sf::st_coordinates(route_xyz)
   d = cumsum(sequential_dist(m, lonlat = lonlat))
   d = c(0, d)
   z = m[, 3]
diff --git a/man/plot_dz.Rd b/man/plot_dz.Rd
index 19f0848..6672f1a 100644
--- a/man/plot_dz.Rd
+++ b/man/plot_dz.Rd
@@ -56,8 +56,8 @@ plot_dz(
 Plot a digital elevation profile based on xyz data
 }
 \examples{
-routes = lisbon_road_segment_3d
-m = sf::st_coordinates(routes)
+route_xyz = lisbon_road_segment_3d
+m = sf::st_coordinates(route_xyz)
 d = cumsum(sequential_dist(m, lonlat = FALSE))
 d = c(0, d)
 z = m[, 3]
diff --git a/man/plot_slope.Rd b/man/plot_slope.Rd
index aa1aea1..7374357 100644
--- a/man/plot_slope.Rd
+++ b/man/plot_slope.Rd
@@ -5,8 +5,8 @@
 \title{Plot slope data for a 3d linestring with base R graphics}
 \usage{
 plot_slope(
-  routes,
-  lonlat = sf::st_is_longlat(routes),
+  route_xyz,
+  lonlat = sf::st_is_longlat(route_xyz),
   fill = TRUE,
   horiz = FALSE,
   p = colorspace::diverging_hcl,
@@ -21,8 +21,8 @@ plot_slope(
 )
 }
 \arguments{
-\item{routes}{Routes, the gradients of which are to be calculated.
-The object must be of class \code{sf} with \code{LINESTRING} geometries.}
+\item{route_xyz}{An sf linestring with x, y and z coordinates,
+representing a route or other linear object.}
 
 \item{lonlat}{Are the coordinates in lon/lat (geographic) coordinates?
 Set this to \code{FALSE} if you have projected data, e.g. with coordinates
@@ -58,7 +58,6 @@ Plot slope data for a 3d linestring with base R graphics
 }
 \examples{
 plot_slope(lisbon_route_3d)
-routes = lisbon_road_segment_3d
-plot_slope(routes)
-routes = lisbon_road_segment_3d
+route_xyz = lisbon_road_segment_3d
+plot_slope(route_xyz)
 }