diff --git a/R/differential.R b/R/differential.R
index 812b5704..c797eec8 100644
--- a/R/differential.R
+++ b/R/differential.R
@@ -182,7 +182,7 @@ diff_expression <- function(object,
     is_hermes_data(object),
     is.string(group)
   )
-  expect_factor(colData(object)[[group]], n.levels = 2L)
+  assert_factor(colData(object)[[group]], n.levels = 2)
 
   method <- match.arg(method, c("voom", "deseq2"))
 
@@ -256,7 +256,7 @@ setMethod(
   definition = function(object,
                         adj_p_val_thresh = 0.05,
                         log2_fc_thresh = 2.5) {
-    expect_proportion(adj_p_val_thresh)
+    assert_proportion(adj_p_val_thresh)
     assert_that(
       is.number(log2_fc_thresh),
       log2_fc_thresh > 0
diff --git a/R/graphs.R b/R/graphs.R
index 9c55e6cf..4d1a7c4f 100644
--- a/R/graphs.R
+++ b/R/graphs.R
@@ -149,7 +149,7 @@ draw_nonzero_boxplot <- function(object,
     is_hermes_data(object),
     is_class(position, "Position")
   )
-  expect_proportion(alpha)
+  assert_proportion(alpha)
 
   no_na_count <- colSums(counts(object) != 0)
   df <- data.frame(no_na = no_na_count, x = "Sample")
diff --git a/R/quality.R b/R/quality.R
index ebbb9e5f..e4071669 100644
--- a/R/quality.R
+++ b/R/quality.R
@@ -36,9 +36,9 @@ control_quality <- function(min_cpm = 1,
   assert_that(
     is.number(min_cpm) && min_cpm >= 0
   )
-  expect_proportion(min_cpm_prop)
-  expect_proportion(min_corr)
-  expect_count(min_depth, positive = TRUE, null.ok = TRUE)
+  assert_proportion(min_cpm_prop)
+  assert_proportion(min_corr)
+  assert_numeric(min_depth, lower = 0, null.ok = TRUE, len = 1)
 
   list(
     min_cpm = min_cpm,
diff --git a/man/h_all_duplicated.Rd b/man/h_all_duplicated.Rd
index 1538b745..6246a9aa 100644
--- a/man/h_all_duplicated.Rd
+++ b/man/h_all_duplicated.Rd
@@ -7,7 +7,8 @@
 h_all_duplicated(x)
 }
 \arguments{
-\item{x}{a vector or a data frame or an array or \code{NULL}.}
+\item{x}{a (generalized, see \code{\link[base]{is.vector}}) vector, a data
+    frame,  an array or \code{NULL}.}
 }
 \value{
 Logical vector flagging all occurrences of duplicate values as \code{TRUE}.