diff --git a/R/mfairELBO.R b/R/mfairELBO.R
index f741b3b..4b72e4d 100644
--- a/R/mfairELBO.R
+++ b/R/mfairELBO.R
@@ -2,12 +2,12 @@
 #'
 #' @param Y Observed main data matrix.
 #' @param object MFAIRSingleFactor object containing the information about the fitted single factor MFAI model.
-#' @param obs_indices Indices of the observed entries in the main data matrix Y. The default value is NULL and used only when Y is stored in the sparse mode.
+#' @param obs_indices Indices of the observed entries in the main data matrix Y and needs to be specified only when Y is stored in the sparse mode. The default value is NULL.
 #'
 #' @return Numeric. The ELBO.
 #' @export
 #'
-getELBO <- function(Y, object, obs_indices) {
+getELBO <- function(Y, object, obs_indices = NULL) {
   N <- nrow(Y)
   M <- ncol(Y)
 
diff --git a/man/getELBO.Rd b/man/getELBO.Rd
index 61f36fd..1243879 100644
--- a/man/getELBO.Rd
+++ b/man/getELBO.Rd
@@ -4,14 +4,14 @@
 \alias{getELBO}
 \title{Compute the evidence lower bound (ELBO) for fitted single factor MFAI model.}
 \usage{
-getELBO(Y, object, obs_indices)
+getELBO(Y, object, obs_indices = NULL)
 }
 \arguments{
 \item{Y}{Observed main data matrix.}
 
 \item{object}{MFAIRSingleFactor object containing the information about the fitted single factor MFAI model.}
 
-\item{obs_indices}{Indices of the observed entries in the main data matrix Y. The default value is NULL and used only when Y is stored in the sparse mode.}
+\item{obs_indices}{Indices of the observed entries in the main data matrix Y and needs to be specified only when Y is stored in the sparse mode. The default value is NULL.}
 }
 \value{
 Numeric. The ELBO.