diff --git a/prll.sh b/prll.sh
index 45a4fa4..f3ec39f 100644
--- a/prll.sh
+++ b/prll.sh
@@ -41,7 +41,7 @@ function prll() {
 	EOF
 	[[ -z "$1" ]] && return 1 || return 0
     fi
-    /usr/bin/which prll_qer > /dev/null
+    @GENTOO_PORTAGE_EPREFIX@/usr/bin/which prll_qer > /dev/null
     if [[ $? -ne 0 ]] ; then
 	echo "PRLL: Missing prll_qer." 1>&2
 	return 1
@@ -51,14 +51,14 @@ function prll() {
 	local prll_unbuffer=yes
 	shift
     else
-	/usr/bin/which prll_bfr > /dev/null
+	@GENTOO_PORTAGE_EPREFIX@/usr/bin/which prll_bfr > /dev/null
 	if [[ $? -ne 0 ]] ; then
 	    echo "PRLL: Missing prll_bfr." 1>&2
 	    return 1
 	fi
     fi
     if [[ -z $PRLL_NR_CPUS ]] ; then
-	/usr/bin/which grep > /dev/null
+	@GENTOO_PORTAGE_EPREFIX@/usr/bin/which grep > /dev/null
 	if [[ $? -ne 0 || ! -a /proc/cpuinfo ]] ; then
 	    echo "PRLL: Environment variable PRLL_NR_CPUS is not set" 1>&2
 	    echo "PRLL: and either the grep utility is missing or" 1>&2