1 files changed, 3 insertions, 0 deletions

diff --git a/src/charset.c b/src/charset.c
index 10627b0970c..3fa9761b988 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -1128,6 +1128,9 @@ DEFUN ("chars-in-region", Fchars_in_region, Schars_in_region, 2, 2, 0,
 {
   int from, to;
 
+  CHECK_NUMBER_COERCE_MARKER (beg, 0);
+  CHECK_NUMBER_COERCE_MARKER (end, 1);
+
   from = min (XFASTINT (beg), XFASTINT (end));
   to = max (XFASTINT (beg), XFASTINT (end));