diff --git a/R/mcmc-distributions.R b/R/mcmc-distributions.R
index 07a1951a..c21d286f 100644
--- a/R/mcmc-distributions.R
+++ b/R/mcmc-distributions.R
@@ -394,7 +394,7 @@ mcmc_violin <- function(
       set_hist_aes(freq),
       fill = get_color("mid"),
       color = get_color("mid_highlight"),
-      size = .25,
+      linewidth = .25,
       na.rm = TRUE,
       binwidth = binwidth,
       bins = bins,
diff --git a/R/ppc-errors.R b/R/ppc-errors.R
index 1bf17b65..510e95f9 100644
--- a/R/ppc-errors.R
+++ b/R/ppc-errors.R
@@ -134,7 +134,7 @@ ppc_error_hist <-
       geom_histogram(
         fill = get_color("l"),
         color = get_color("lh"),
-        size = 0.25,
+        linewidth = 0.25,
         binwidth = binwidth,
         bins = bins,
         breaks = breaks
diff --git a/R/ppd-distributions.R b/R/ppd-distributions.R
index bbf67218..7c868311 100644
--- a/R/ppd-distributions.R
+++ b/R/ppd-distributions.R
@@ -168,7 +168,7 @@ ppd_hist <-
       fill = "ypred"
     )) +
       geom_histogram(
-        size = 0.25,
+        linewidth = 0.25,
         binwidth = binwidth,
         bins = bins,
         breaks = breaks
diff --git a/tests/testthat/test-mcmc-traces.R b/tests/testthat/test-mcmc-traces.R
index 62d46c88..86679647 100644
--- a/tests/testthat/test-mcmc-traces.R
+++ b/tests/testthat/test-mcmc-traces.R
@@ -51,7 +51,11 @@ test_that("mcmc_trace options work", {
   expect_equal(g1$coordinates$limits$x, c(5, 10))
 
   expect_gg(g2 <- mcmc_trace(arr, regex_pars = "beta", n_warmup = 10))
-  ll <- g2$labels
+  if ("get_labs" %in% getNamespaceExports("ggplot2")) {
+    ll <- ggplot2::get_labs(g2)
+  } else {
+    ll <- g2$labels
+  }
   expect_true(all(c("xmin", "xmax", "ymin", "ymax") %in% names(ll)))
 
   expect_error(mcmc_trace(arr, iter1 = -1))