diff --git a/which.spec b/which.spec
index e3fe1e9..0c2e87b 100644
--- a/which.spec
+++ b/which.spec
@@ -1,7 +1,7 @@
 Summary: Displays where a particular program in your path is located
 Name: which
 Version: 2.21
-Release: 25%{?dist}
+Release: 26%{?dist}
 License: GPLv3
 Source0: http://ftp.gnu.org/gnu/which/%{name}-%{version}.tar.gz
 Source1: which2.sh
@@ -40,6 +40,9 @@ rm -f $RPM_BUILD_ROOT%{_infodir}/dir
 %{_mandir}/man1/which.1*
 
 %changelog
+* Fri May 07 2021 Than Ngo <than@redhat.com> - 2.21-26
+- Related: #1940464, fixed unbound variable
+
 * Fri Apr 16 2021 Mohan Boddu <mboddu@redhat.com> - 2.21-25
 - Rebuilt for RHEL 9 BETA on Apr 15th 2021. Related: rhbz#1947937
 
diff --git a/which2.sh b/which2.sh
index 2b8b20a..6ef7979 100644
--- a/which2.sh
+++ b/which2.sh
@@ -1,18 +1,19 @@
 # shellcheck shell=sh
 # Initialization script for bash, sh, mksh and ksh
 
-_declare="declare -f"
-_opt="-f"
-_shell="$(basename $SHELL)"
+which_declare="declare -f"
+which_opt="-f"
+which_shell="$(cat /proc/$$/comm)"
 
-if [ "$_shell" = "ksh" ] || [ "$_shell" = "mksh" ] || [ "$_shell" = "zsh" ] ; then
-  _declare="typeset -f"
-  _opt=""
+if [ "$which_shell" = "ksh" ] || [ "$which_shell" = "mksh" ] || [ "$which_shell" = "zsh" ] ; then
+  which_declare="typeset -f"
+  which_opt=""
 fi
  
 which ()
 {
-(alias; eval ${_declare}) | /usr/bin/which --tty-only --read-alias --read-functions --show-tilde --show-dot "$@"
+(alias; eval ${which_declare}) | /usr/bin/which --tty-only --read-alias --read-functions --show-tilde --show-dot "$@"
 }
 
-export ${_opt} which
+export which_declare
+export ${which_opt} which