diff --git a/configure.ac b/configure.ac
index 4d548de1..38531960 100644
--- a/configure.ac
+++ b/configure.ac
@@ -205,7 +205,7 @@ AC_PROG_RANLIB
 dnl Bash must be at least version 4.  If it is too old, fail hard
 dnl with a good diagnostic.  Note macOS ships an ancient version
 dnl of bash (https://gitlab.com/nbdkit/nbdkit/-/issues/21)
-bash=`which bash`
+bash=$(command -v bash)
 AC_MSG_CHECKING([for the major version of $bash])
 bash_major=`bash -c 'echo ${BASH_VERSINFO:-0}'`
 AC_MSG_RESULT([$bash_major])