diff --git a/tests/http2-server.pl b/tests/http2-server.pl
index 52c5284c0c..d4367da636 100755
--- a/tests/http2-server.pl
+++ b/tests/http2-server.pl
@@ -116,4 +116,4 @@ my $cmdline="$nghttpx --backend=$connect ".
     "--errorlog-file=$logfile ".
     "$keyfile $certfile";
 print "RUN: $cmdline\n" if($verbose);
-system("$cmdline 2>/dev/null");
+exec("exec $cmdline 2>/dev/null");
diff --git a/tests/http3-server.pl b/tests/http3-server.pl
index bc9e98ad11..97e6998be0 100755
--- a/tests/http3-server.pl
+++ b/tests/http3-server.pl
@@ -116,4 +116,4 @@ my $cmdline="$nghttpx --http2-proxy --backend=$connect ".
     "--conf=$conf ".
     "$keyfile $certfile";
 print "RUN: $cmdline\n" if($verbose);
-system("$cmdline 2>/dev/null");
+exec("exec $cmdline 2>/dev/null");