diff --git a/SOURCES/which2.sh b/SOURCES/which2.sh
index 8fc0284..2b8b20a 100644
--- a/SOURCES/which2.sh
+++ b/SOURCES/which2.sh
@@ -3,8 +3,9 @@
 
 _declare="declare -f"
 _opt="-f"
+_shell="$(basename $SHELL)"
 
-if [ "$0" = "ksh" ] || [ "$0" = "-ksh" ] || [ "$0" = "mksh" ] || [ "$0" = "-mksh" ] ; then
+if [ "$_shell" = "ksh" ] || [ "$_shell" = "mksh" ] || [ "$_shell" = "zsh" ] ; then
   _declare="typeset -f"
   _opt=""
 fi
diff --git a/SPECS/which.spec b/SPECS/which.spec
index 2838787..299703c 100644
--- a/SPECS/which.spec
+++ b/SPECS/which.spec
@@ -1,7 +1,7 @@
 Summary: Displays where a particular program in your path is located
 Name: which
 Version: 2.21
-Release: 13%{?dist}
+Release: 14%{?dist}
 License: GPLv3
 Source0: http://ftp.gnu.org/gnu/which/%{name}-%{version}.tar.gz
 Source1: which2.sh
@@ -41,6 +41,9 @@ rm -f $RPM_BUILD_ROOT%{_infodir}/dir
 %{_mandir}/man1/which.1*
 
 %changelog
+* Tue Mar 23 2021 Than Ngo <than@redhat.com> - 2.21-14
+- Related: #1940468, fix regression if SHELL=zsh
+
 * Fri Mar 19 2021 Than Ngo <than@redhat.com> - 2.21-13
 - Resolves: #1940468, fixed syntax error caused by testcase: a=b which ls
   Coverity issue