diff --git a/lshmm/api.py b/lshmm/api.py
index e8619e4..2e37c6b 100644
--- a/lshmm/api.py
+++ b/lshmm/api.py
@@ -56,7 +56,7 @@ def check_inputs(
     :param numpy.ndarray prob_recombination: Recombination probability.
     :param numpy.ndarray prob_mutation: Mutation probability.
     :param bool scale_mutation_rate: Scale mutation rate.
-    :return: Number of reference haplotypes, number of sites, ploidy
+    :return: Number of ref. haplotypes, number of sites, ploidy, emission prob. matrix.
     :rtype: tuple
     """
     # Check the reference panel.