diff --git a/CommandLines.h b/CommandLines.h
index b61d863..c09d445 100644
--- a/CommandLines.h
+++ b/CommandLines.h
@@ -3,7 +3,7 @@
 
 #include <pthread.h>
 
-#define HA_VERSION "0.3.0-dirty-r235"
+#define HA_VERSION "0.3.0-dirty-r237"
 
 #define VERBOSE 0
 
diff --git a/Hash_Table.cpp b/Hash_Table.cpp
index c156f9d..bc23fb5 100644
--- a/Hash_Table.cpp
+++ b/Hash_Table.cpp
@@ -371,6 +371,7 @@ int32_t ha_chain_lis_core(k_mer_hit *a, int32_t n_a, Chain_Data *dp, int32_t min
 			b[i] = i;
 		m = n_a;
 	} else m = ha_kmer_hit_lis(n_a, a, b, M);
+	if (m < n_a>>1) return -1;
 	bw_pen = 1.0 / bw_thres;
 	dp->score[0] = a[b[0]].good? min_sc : min_sc>>1;
 	dp->pre[0] = -1, dp->indels[0] = 0, dp->self_length[0] = 0;