diff --git a/meta/recipes-kernel/perf/perf_3.4.bb b/meta/recipes-kernel/perf/perf_3.4.bb
index decc911..6e1c746 100644
--- a/meta/recipes-kernel/perf/perf_3.4.bb
+++ b/meta/recipes-kernel/perf/perf_3.4.bb
@@ -74,7 +74,7 @@ do_compile() {
 do_install() {
 	oe_runmake DESTDIR=${D} install
 	# we are checking for this make target to be compatible with older perf versions
-	if [ "${@perf_feature_enabled('perf-scripting', 1, 0, d)}" = "1" -a $(grep install-python_ext ${S}/tools/perf/Makefile) = "0"]; then
+	if [ "${@perf_feature_enabled('perf-scripting', 1, 0, d)}" = "1" ] && ! grep -q install-python_ext ${S}/tools/perf/Makefile  ]; then
 		oe_runmake DESTDIR=${D} install-python_ext
 	fi
 }