https://bugs.gentoo.org/844886
--- a/configure
+++ b/configure
@@ -26,7 +26,7 @@ msg_chkfor() {
 check_docs() {
 
     msg_chkfor "asciidoc"
-    if which asciidoc 1> /dev/null 2>&3
+    if command -v asciidoc 1> /dev/null 2>&3
     then
         echo "ok."
         echo "#_______________________" >&4
@@ -40,7 +40,7 @@ check_docs() {
 check_tools() {
 
     msg_chkfor "compiler $CC"
-    if which "$CC" 1> /dev/null 2>&3
+    if command -v "$CC" 1> /dev/null 2>&3
     then
         echo "ok."
         echo "---------------------------------" 1>&3
@@ -56,7 +56,7 @@ check_tools() {
 check_imlib2() {
 
     msg_chkfor "imlib2-config"
-    if which imlib2-config 1> /dev/null 2>&3
+    if command -v imlib2-config 1> /dev/null 2>&3
     then
         echo "ok."
         cat << EOF > tmp.c