diff --git a/src/load_layout.c b/src/load_layout.c
index 632c6ec7..7961e17f 100644
--- a/src/load_layout.c
+++ b/src/load_layout.c
@@ -157,6 +157,7 @@ static int json_end_map(void *ctx) {
             }
 
             free(marks);
+            marks = NULL;
             num_marks = 0;
         }