diff --git a/DESCRIPTION b/DESCRIPTION
index 7d61265..f175d6e 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -42,3 +42,4 @@ Enhances:
   rstanarm
 VignetteBuilder: knitr
 Roxygen: list(markdown = TRUE)
+RoxygenNote: 7.2.3
diff --git a/NAMESPACE b/NAMESPACE
index 61122ac..0ff33ff 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -50,6 +50,7 @@ importFrom(stats,as.formula)
 importFrom(stats,coef)
 importFrom(stats,coefficients)
 importFrom(stats,complete.cases)
+importFrom(stats,contrasts)
 importFrom(stats,df.residual)
 importFrom(stats,ecdf)
 importFrom(stats,family)
@@ -70,5 +71,7 @@ importFrom(stats,residuals)
 importFrom(stats,sd)
 importFrom(stats,terms)
 importFrom(stats,update)
+importFrom(stats,update.formula)
 importFrom(stats,vcov)
 importFrom(stats,weighted.mean)
+importFrom(utils,methods)
diff --git a/R/simple_margins.R b/R/simple_margins.R
index 5765fd0..baf96cf 100644
--- a/R/simple_margins.R
+++ b/R/simple_margins.R
@@ -185,7 +185,7 @@ sim_margins <- function(model, pred, modx, mod2 = NULL, modx.values = NULL,
     at_list[[mod2]] <- mod2vals2
   }
 
-  design <- if ("svyglm" %in% class(model)) model$survey.design else NULL
+  design <- if (inherits(model, "svyglm")) model$survey.design else NULL
 
   # Get the margins
   suppressWarnings({ # can't have confusing warnings from margins
@@ -274,7 +274,7 @@ print.sim_margins <- function(x, ...) {
 
       m <- ss$slopes[[j]]
 
-      if (class(x$mod2.values) != "character") {
+      if (inherits(x$mod2.values, "character")) {
         m[x$mod2] <- num_print(m[x$mod2], x$digits)
       }
 
@@ -312,7 +312,7 @@ print.sim_margins <- function(x, ...) {
 
     for (i in seq_along(x$modx.values)) {
 
-      if (class(x$modx.values) != "character") {
+      if (inherits(x$modx.values, "character")) {
         m[x$modx] <- num_print(m[x$modx], digits = x$digits)
       }
 
@@ -398,7 +398,7 @@ tidy.sim_margins <- function(x, conf.level = .95, ...) {
     base$conf.high <- all_slopes[,make_ci_labs(conf.level)[[2]]]
   } else { # If not, calculate them
     alpha <- (1 - conf.level) / 2
-    crit_t <- if (class(x$mods[[1]]) == "lm") {
+    crit_t <- if (inherits(x$mods[[1]], "lm")) {
       abs(qt(alpha, df = df.residual(x$mods[[1]])))
     } else {
       abs(qnorm(alpha))
diff --git a/R/simple_slopes.R b/R/simple_slopes.R
index aad76e7..c1b04ca 100644
--- a/R/simple_slopes.R
+++ b/R/simple_slopes.R
@@ -118,7 +118,8 @@
 #' sim_slopes(regmodel, pred = ell, modx = meals, mod2 = sch.wide)
 #' }
 #'
-#' @importFrom stats coef coefficients lm predict sd update getCall vcov relevel
+#' @importFrom stats coef coefficients lm predict sd update getCall vcov 
+#' @importFrom stats relevel contrasts
 #' @import jtools
 #' @export
 #'
@@ -212,7 +213,7 @@ sim_slopes <- function(model, pred, modx, mod2 = NULL, modx.values = NULL,
   # Only keep the ones represented among the coefficients
   if (!is.null(attr(class(model), "package")) && "lme4" %in%
         attr(class(model), "package")) {
-    pred_names <- pred_names %just% names(fixef(model))
+    pred_names <- pred_names %just% names(lme4::fixef(model))
   } else {
     pred_names <- pred_names %just% names(coef(model))
   }
diff --git a/R/utils.R b/R/utils.R
index ed380af..49217b5 100644
--- a/R/utils.R
+++ b/R/utils.R
@@ -165,8 +165,7 @@ cut2 <- function(x, cuts, m = 150, g, levels.mean = FALSE,
                 "\nUpper endpoints:", paste(format(up, digits = 12),
                                             collapse = " "))
     y <- structure(y, class = "factor", levels = labs)
-  }
-  else {
+  } else {
     if (minmax) {
       r <- range(x, na.rm = TRUE)
       if (r[1] < cuts[1])
@@ -289,6 +288,7 @@ j_update <- function(mod, formula = NULL, data = NULL, offset = NULL,
 # Looking for whether a method is defined for a given object (...)
 # getS3method() doesn't work for something like merMod because the string
 # "merMod" is not in the vector returned by class()
+#' @importFrom utils methods
 check_method <- function(generic, ...) {
   ch <- deparse(substitute(generic))
   f <- X <- function(x, ...) UseMethod("X")