diff --git a/sys.c b/sys.c
index 3d54f68..502e32f 100644
--- a/sys.c
+++ b/sys.c
@@ -217,6 +217,9 @@ sys_proc_info(pid_t pid, char **path, uid_t *uid, gid_t *gid) {
 
 	/* fetch process path */
 	*path = malloc(PROC_PIDPATHINFO_MAXSIZE);
+	if (!*path) {
+		return -1;
+	}
 	int path_len = proc_pidpath(pid, *path, PROC_PIDPATHINFO_MAXSIZE);
 	if (path_len == -1) {
 		free(*path);
@@ -238,7 +241,7 @@ char *
 sys_user_str(uid_t uid)
 {
 	int bufsize;
-        if ((bufsize = sysconf(_SC_GETPW_R_SIZE_MAX)) == -1) {
+	if ((bufsize = sysconf(_SC_GETPW_R_SIZE_MAX)) == -1) {
 		log_err_printf("failed to get password bufsize: %s\n",
 		               strerror(errno));
 		return NULL;
diff --git a/sys.h b/sys.h
index 537ab1b..2412c48 100644
--- a/sys.h
+++ b/sys.h
@@ -41,7 +41,7 @@ int sys_pidf_open(const char *) NONNULL(1) WUNRES;
 int sys_pidf_write(int) WUNRES;
 void sys_pidf_close(int, const char *) NONNULL(2);
 
-int sys_proc_info(pid_t, char **, uid_t *, gid_t *) WUNRES;
+int sys_proc_info(pid_t, char **, uid_t *, gid_t *) WUNRES NONNULL(2,3,4);
 
 char * sys_user_str(uid_t) WUNRES MALLOC;
 char * sys_group_str(gid_t) WUNRES MALLOC;