diff --git a/src/target/cortex_m.c b/src/target/cortex_m.c
index b55de1bc6..88b226d85 100644
--- a/src/target/cortex_m.c
+++ b/src/target/cortex_m.c
@@ -1865,6 +1865,7 @@ static void cortex_m_dwt_free(struct target *target)
 
 	free(cm->dwt_comparator_list);
 	cm->dwt_comparator_list = NULL;
+	cm->dwt_num_comp = 0;
 
 	if (cache) {
 		register_unlink_cache(&target->reg_cache, cache);