diff --git a/src/basic/xattr-util.c b/src/basic/xattr-util.c
index 1d045f911b..ab321e0293 100644
--- a/src/basic/xattr-util.c
+++ b/src/basic/xattr-util.c
@@ -27,7 +27,7 @@ int getxattr_malloc(const char *path, const char *name, char **value, bool allow
         assert(name);
         assert(value);
 
-        for (l = 100; ; l = (size_t) n + 1) {
+        for (l = 100; ; l = (size_t) n + 1 /* extra byte to make sure this remains NUL suffixed */) {
                 v = new0(char, l);
                 if (!v)
                         return -ENOMEM;
@@ -36,7 +36,6 @@ int getxattr_malloc(const char *path, const char *name, char **value, bool allow
                         n = lgetxattr(path, name, v, l);
                 else
                         n = getxattr(path, name, v, l);
-
                 if (n >= 0 && (size_t) n < l) {
                         *value = v;
                         return n;
@@ -65,13 +64,12 @@ int fgetxattr_malloc(int fd, const char *name, char **value) {
         assert(name);
         assert(value);
 
-        for (l = 100; ; l = (size_t) n + 1) {
+        for (l = 100;; l = (size_t) n + 1 /* extra byte to make sure this remains NUL suffixed */) {
                 v = new0(char, l);
                 if (!v)
                         return -ENOMEM;
 
                 n = fgetxattr(fd, name, v, l);
-
                 if (n >= 0 && (size_t) n < l) {
                         *value = v;
                         return n;