diff --git a/DESCRIPTION b/DESCRIPTION
index b5d64b2e..29ca554b 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -22,7 +22,7 @@ Imports:
     recipes (>= 1.0.4),
     rsample,
     dplyr (>= 1.0.0),
-    ggplot2,
+    ggplot2 (>= 3.4.0),
     forcats,
     stringr,
     plotly,
diff --git a/R/plot-acf_diagnostics.R b/R/plot-acf_diagnostics.R
index 7015a562..8e17ade8 100644
--- a/R/plot-acf_diagnostics.R
+++ b/R/plot-acf_diagnostics.R
@@ -18,7 +18,7 @@
 #' @param .facet_ncol Facets: Number of facet columns. Has no effect if using `grouped_df`.
 #' @param .facet_scales Facets: Options include "fixed", "free", "free_y", "free_x"
 #' @param .line_color Line color. Use keyword: "scale_color" to change the color by the facet.
-#' @param .line_size Line size
+#' @param .line_size Line size (linewidth)
 #' @param .line_alpha Line opacity. Adjust the transparency of the line. Range: (0, 1)
 #' @param .point_color Point color. Use keyword: "scale_color" to change the color by the facet.
 #' @param .point_size Point size
@@ -215,11 +215,11 @@ plot_acf_diagnostics.data.frame <- function(.data, .date_var, .value, .ccf_vars
     if (.line_color == "scale_color") {
         g <- g +
             ggplot2::geom_line(ggplot2::aes(color = name),
-                               size = .line_size, alpha = .line_alpha) +
+                               linewidth = .line_size, alpha = .line_alpha) +
             scale_color_tq()
     } else {
         g <- g +
-            ggplot2::geom_line(color = .line_color, size = .line_size, alpha = .line_alpha)
+            ggplot2::geom_line(color = .line_color, linewidth = .line_size, alpha = .line_alpha)
     }
 
     # Add points
@@ -335,11 +335,11 @@ plot_acf_diagnostics.grouped_df <- function(.data, .date_var, .value, .ccf_vars
     if (.line_color == "scale_color") {
         g <- g +
             ggplot2::geom_line(ggplot2::aes(color = .groups_consolidated),
-                               size = .line_size, alpha = .line_alpha) +
+                               linewidth = .line_size, alpha = .line_alpha) +
             scale_color_tq()
     } else {
         g <- g +
-            ggplot2::geom_line(color = .line_color, size = .line_size, alpha = .line_alpha)
+            ggplot2::geom_line(color = .line_color, linewidth = .line_size, alpha = .line_alpha)
     }
 
     # Add points
diff --git a/R/plot-anomaly_diagnostics.R b/R/plot-anomaly_diagnostics.R
index a99034c1..6428c8a2 100644
--- a/R/plot-anomaly_diagnostics.R
+++ b/R/plot-anomaly_diagnostics.R
@@ -301,10 +301,10 @@ plot_anomaly_diagnostics.data.frame <- function(
     # Add line
     g <- g +
         ggplot2::geom_line(
-            color    = .line_color,
-            size     = .line_size,
-            linetype = .line_type,
-            alpha    = .line_alpha
+            color     = .line_color,
+            linewidth = .line_size,
+            linetype  = .line_type,
+            alpha     = .line_alpha
         )
 
     # Add Outliers
diff --git a/R/plot-time_series.R b/R/plot-time_series.R
index 69e3a534..f614ebb8 100644
--- a/R/plot-time_series.R
+++ b/R/plot-time_series.R
@@ -361,19 +361,19 @@ plot_time_series.data.frame <- function(
     if (rlang::quo_is_null(color_var_expr)) {
         g <- g +
             ggplot2::geom_line(
-                color    = .line_color,
-                size     = .line_size,
-                linetype = .line_type,
-                alpha    = .line_alpha
+                color     = .line_color,
+                linewidth = .line_size,
+                linetype  = .line_type,
+                alpha     = .line_alpha
             )
 
     } else {
         g <- g +
             ggplot2::geom_line(
                 ggplot2::aes(color = .color_mod, group = .color_mod),
-                size     = .line_size,
-                linetype = .line_type,
-                alpha    = .line_alpha
+                linewidth = .line_size,
+                linetype  = .line_type,
+                alpha     = .line_alpha
             ) +
             scale_color_tq()
     }
diff --git a/R/tidyquant-theme-compat.R b/R/tidyquant-theme-compat.R
index 2fb917f9..a1973a68 100644
--- a/R/tidyquant-theme-compat.R
+++ b/R/tidyquant-theme-compat.R
@@ -15,10 +15,10 @@ theme_tq <- function(base_size = 11, base_family = "") {
         ggplot2::theme(
 
             # Base Inherited Elements
-            line               =  ggplot2::element_line(colour = blue, size = 0.5, linetype = 1,
+            line               =  ggplot2::element_line(colour = blue, linewidth = 0.5, linetype = 1,
                                                         lineend = "butt"),
             rect               =  ggplot2::element_rect(fill = white, colour = blue,
-                                                        size = 0.5, linetype = 1),
+                                                        linewidth = 0.5, linetype = 1),
             text               =  ggplot2::element_text(family = base_family, face = "plain",
                                                         colour = blue, size = base_size,
                                                         lineheight = 0.9, hjust = 0.5, vjust = 0.5, angle = 0,
@@ -27,14 +27,14 @@ theme_tq <- function(base_size = 11, base_family = "") {
             # Axes
             axis.line          = ggplot2::element_blank(),
             axis.text          = ggplot2::element_text(size = ggplot2::rel(0.8)),
-            axis.ticks         = ggplot2::element_line(color = grey, size = ggplot2::rel(1/3)),
+            axis.ticks         = ggplot2::element_line(color = grey, linewidth = ggplot2::rel(1/3)),
             axis.title         = ggplot2::element_text(size = ggplot2::rel(1.0)),
 
             # Panel
             panel.background   = ggplot2::element_rect(fill = white, color = NA),
-            panel.border       = ggplot2::element_rect(fill = NA, size = ggplot2::rel(1/2), color = blue),
-            panel.grid.major   = ggplot2::element_line(color = grey, size = ggplot2::rel(1/3)),
-            panel.grid.minor   = ggplot2::element_line(color = grey, size = ggplot2::rel(1/3)),
+            panel.border       = ggplot2::element_rect(fill = NA, linewidth = ggplot2::rel(1/2), color = blue),
+            panel.grid.major   = ggplot2::element_line(color = grey, linewidth = ggplot2::rel(1/3)),
+            panel.grid.minor   = ggplot2::element_line(color = grey, linewidth = ggplot2::rel(1/3)),
             panel.grid.minor.x = ggplot2::element_blank(),
             panel.spacing      = ggplot2::unit(.75, "cm"),
 
@@ -70,12 +70,12 @@ theme_tq_dark <- function(base_size = 11, base_family = "") {
         ggplot2::theme(
 
             # Axes
-            axis.ticks         = ggplot2::element_line(color = blue, size = ggplot2::rel(1/3)),
+            axis.ticks         = ggplot2::element_line(color = blue, linewidth = ggplot2::rel(1/3)),
 
             # Panel
             panel.background   = ggplot2::element_rect(fill = grey, color = NA),
-            panel.grid.major   = ggplot2::element_line(color = white, size = ggplot2::rel(1/3)),
-            panel.grid.minor   = ggplot2::element_line(color = white, size = ggplot2::rel(1/3)),
+            panel.grid.major   = ggplot2::element_line(color = white, linewidth = ggplot2::rel(1/3)),
+            panel.grid.minor   = ggplot2::element_line(color = white, linewidth = ggplot2::rel(1/3)),
 
             # Complete theme
             complete = TRUE
@@ -95,12 +95,12 @@ theme_tq_green <- function(base_size = 11, base_family = "") {
         ggplot2::theme(
 
             # Axes
-            axis.ticks         = ggplot2::element_line(color = blue, size = ggplot2::rel(1/3)),
+            axis.ticks         = ggplot2::element_line(color = blue, linewidth = ggplot2::rel(1/3)),
 
             # Panel
             panel.background   = ggplot2::element_rect(fill = green, color = NA),
-            panel.grid.major   = ggplot2::element_line(color = white, size = ggplot2::rel(1/3)),
-            panel.grid.minor   = ggplot2::element_line(color = white, size = ggplot2::rel(1/3)),
+            panel.grid.major   = ggplot2::element_line(color = white, linewidth = ggplot2::rel(1/3)),
+            panel.grid.minor   = ggplot2::element_line(color = white, linewidth = ggplot2::rel(1/3)),
 
             # Complete theme
             complete = TRUE
diff --git a/man/plot_acf_diagnostics.Rd b/man/plot_acf_diagnostics.Rd
index 16719105..ff7825b8 100644
--- a/man/plot_acf_diagnostics.Rd
+++ b/man/plot_acf_diagnostics.Rd
@@ -56,7 +56,7 @@ versus the \code{.value}. Useful for evaluating external lagged regressors.}
 
 \item{.line_color}{Line color. Use keyword: "scale_color" to change the color by the facet.}
 
-\item{.line_size}{Line size}
+\item{.line_size}{Line size (linewidth)}
 
 \item{.line_alpha}{Line opacity. Adjust the transparency of the line. Range: (0, 1)}