diff --git a/hit.c b/hit.c
index ddbf19b..ebc0f68 100644
--- a/hit.c
+++ b/hit.c
@@ -130,7 +130,7 @@ void mm_sync_regs(void *km, int n_regs, mm_reg1_t *regs) // keep mm_reg1_t::{id,
 {
 	int *tmp, i, max_id = -1, n_tmp, n_pri;
 	if (n_regs <= 0) return;
-	for (i = 0; i < n_regs; ++i)
+	for (i = 0; i < n_regs; ++i) // NB: doesn't work if mm_reg1_t::id is negative
 		max_id = max_id > regs[i].id? max_id : regs[i].id;
 	n_tmp = max_id + 1;
 	tmp = (int*)kmalloc(km, n_tmp * sizeof(int));
@@ -187,7 +187,6 @@ void mm_filter_regs(void *km, const mm_mapopt_t *opt, int *n_regs, mm_reg1_t *re
 		}
 	}
 	*n_regs = k;
-	mm_sync_regs(km, k, regs);
 }
 
 int mm_squeeze_a(void *km, int n_regs, mm_reg1_t *regs, mm128_t *a)
@@ -260,6 +259,7 @@ void mm_join_long(void *km, const mm_mapopt_t *opt, int qlen, int *n_regs_, mm_r
 			}
 		}
 		mm_filter_regs(km, opt, n_regs_, regs);
+		mm_sync_regs(km, *n_regs_, regs);
 	}
 }
 
diff --git a/main.c b/main.c
index a0115ad..e7e7232 100644
--- a/main.c
+++ b/main.c
@@ -10,7 +10,7 @@
 #include "minimap.h"
 #include "mmpriv.h"
 
-#define MM_VERSION "2.0-r149-pre"
+#define MM_VERSION "2.0-r150-pre"
 
 void liftrlimit()
 {
diff --git a/map.c b/map.c
index 9f18cc7..bb84703 100644
--- a/map.c
+++ b/map.c
@@ -250,7 +250,7 @@ mm_reg1_t *mm_map_frag(const mm_mapopt_t *opt, const mm_idx_t *mi, mm_tbuf_t *b,
 			mm_set_parent(b->km, opt->mask_level, *n_regs, regs);
 			mm_select_sub(b->km, opt->mask_level, opt->pri_ratio, opt->best_n, n_regs, regs);
 		}
-	} else mm_filter_regs(b->km, opt, n_regs, regs);
+	}
 	mm_set_mapq(*n_regs, regs);
 
 	// free