diff --git a/R/getDegTx.R b/R/getDegTx.R
index ef5c6d2..fa64584 100644
--- a/R/getDegTx.R
+++ b/R/getDegTx.R
@@ -37,6 +37,9 @@ getDegTx <- function(rse_tx, type = c("cell_component", "standard", "top1500"),
   
   type = arg_match(type)
   
+  # Check if assayname is in assayNames
+  stopifnot(assayname %in% assayNames(rse_tx))
+  
   # Validate rse_tx is a RangedSummarizedExperiment object
   if (!is(rse_tx, "RangedSummarizedExperiment")) {
     stop("rse_tx must be a RangedSummarizedExperiment object.")