diff --git a/src/core/namespace.c b/src/core/namespace.c
index 058b691a4a..5dd2cc7c3a 100644
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -365,9 +365,7 @@ static int prefix_where_needed(MountEntry *m, unsigned n, const char *root_direc
                 if (!s)
                         return -ENOMEM;
 
-                free(m[i].path_malloc);
-                m[i].path_malloc = s;
-
+                free_and_replace(m[i].path_malloc, s);
                 m[i].has_prefix = true;
         }