diff --git a/R/analyze.R b/R/analyze.R
index 3acaf9b..3b637c7 100644
--- a/R/analyze.R
+++ b/R/analyze.R
@@ -15,7 +15,7 @@
 #'
 #' @export
 analyze <- function(preset, progress = NULL) {
-    if (class(preset) != "geposan_preset") {
+    if (!inherits(preset, "geposan_preset")) {
         stop("Preset is invalid. Use geposan::preset() to create one.")
     }
 
diff --git a/R/comparison.R b/R/comparison.R
index 082d524..c9233bb 100644
--- a/R/comparison.R
+++ b/R/comparison.R
@@ -18,7 +18,7 @@
 #'
 #' @export
 compare <- function(ranking, comparison_gene_ids) {
-    if (!"geposan_ranking" %chin% class(ranking)) {
+    if (!inherits(ranking, "geposan_ranking")) {
         stop("Invalid ranking. Use geposan::ranking().")
     }
 
diff --git a/R/ranking.R b/R/ranking.R
index 6782a98..a4d9816 100644
--- a/R/ranking.R
+++ b/R/ranking.R
@@ -13,9 +13,9 @@
 #'
 #' @export
 ranking <- function(analysis, weights) {
-    if ("geposan_analysis" %chin% class(analysis)) {
+    if (inherits(analysis, "geposan_analysis")) {
         ranking <- copy(analysis$ranking)
-    } else if ("geposan_results" %chin% class(analysis)) {
+    } else if (inherits(analysis, "geposan_results")) {
         ranking <- copy(analysis)
     } else {
         stop("Invalid analyis. Use geposan::analyze().")
@@ -60,7 +60,7 @@ ranking <- function(analysis, weights) {
 #' @export
 optimal_weights <- function(analysis, methods, reference_gene_ids,
                             target = "mean") {
-    if (!any(c("geposan_analysis", "geposan_results") %chin% class(analysis))) {
+    if (!inherits(analysis, c("geposan_analysis", "geposan_results"))) {
         stop("Invalid analyis. Use geposan::analyze().")
     }
 
diff --git a/R/validate.R b/R/validate.R
index 5950fd3..fe8da66 100644
--- a/R/validate.R
+++ b/R/validate.R
@@ -12,7 +12,7 @@
 #'
 #' @export
 validate <- function(analysis, progress = NULL) {
-    if (class(analysis) != "geposan_analysis") {
+    if (inherits(analysis, "geposan_analysis")) {
         stop("Analysis is invalid. Use geposan::analyze().")
     }