diff --git a/tools/perf/scripts/python/bin/syscall-counts-by-pid-report b/tools/perf/scripts/python/bin/syscall-counts-by-pid-report
index c53362e..9e9d8dd 100644
--- a/tools/perf/scripts/python/bin/syscall-counts-by-pid-report
+++ b/tools/perf/scripts/python/bin/syscall-counts-by-pid-report
@@ -2,7 +2,7 @@
 # description: system-wide syscall counts, by pid
 # args: [comm]
 if [ $# -gt 0 ] ; then
-    if ! expr match "$1" "-" ; then
+    if ! expr match "$1" "-" > /dev/null ; then
 	comm=$1
 	shift
     fi