diff --git a/tools/test-runner.c b/tools/test-runner.c
index b25aa19a..ceaa6531 100644
--- a/tools/test-runner.c
+++ b/tools/test-runner.c
@@ -345,8 +345,8 @@ static bool check_virtualization(void)
 
 static void start_qemu(void)
 {
-	char cwd[PATH_MAX], initcmd[PATH_MAX], testargs[PATH_MAX];
-	char cmdline[CMDLINE_MAX];
+	char cwd[PATH_MAX], testargs[PATH_MAX];
+	char *initcmd, *cmdline;
 	char **argv;
 	int i, pos;
 	bool has_virt;
@@ -357,9 +357,9 @@ static void start_qemu(void)
 		strcat(cwd, "/");
 
 	if (own_binary[0] == '/')
-		snprintf(initcmd, sizeof(initcmd), "%s", own_binary);
+		initcmd = l_strdup_printf("%s", own_binary);
 	else
-		snprintf(initcmd, sizeof(initcmd), "%s/%s", cwd, own_binary);
+		initcmd = l_strdup_printf("%s/%s", cwd, own_binary);
 
 	pos = snprintf(testargs, sizeof(testargs), "%s", test_argv[0]);
 
@@ -370,7 +370,7 @@ static void start_qemu(void)
 		pos += snprintf(testargs + pos, len, " %s", test_argv[i]);
 	}
 
-	snprintf(cmdline, sizeof(cmdline),
+	cmdline = l_strdup_printf(
 			"console=ttyS0,115200n8 earlyprintk=serial "
 			"rootfstype=9p "
 			"root=/dev/root "
@@ -408,6 +408,10 @@ static void start_qemu(void)
 	argv[pos] = NULL;
 
 	execve(argv[0], argv, qemu_envp);
+
+	/* Don't expect to reach here */
+	free(initcmd);
+	free(cmdline);
 }
 
 static pid_t execute_program(char *argv[], bool wait, bool verbose)
@@ -1942,19 +1946,19 @@ static void test_stat_queue_entry_destroy(void *data)
 
 static void run_auto_tests(void)
 {
-	char test_home_path[PATH_MAX];
-	char env_path[PATH_MAX];
+	L_AUTO_FREE_VAR(char*, test_home_path);
+	L_AUTO_FREE_VAR(char*, env_path);
 	int i;
 	struct l_hashmap *test_config_map;
 	struct l_queue *test_stat_queue;
 	char **test_config_dirs;
 
-	sprintf(env_path, "%s/src:%s/tools:%s", top_level_path, top_level_path,
-								getenv("PATH"));
+	env_path = l_strdup_printf("%s/src:%s/tools:%s", top_level_path,
+					top_level_path, getenv("PATH"));
 
 	setenv("PATH", env_path, true);
 
-	sprintf(test_home_path, "%s/%s", top_level_path,
+	test_home_path = l_strdup_printf("%s/%s", top_level_path,
 						TEST_TOP_DIR_DEFAULT_NAME);
 
 	if (!path_exist(test_home_path)) {