diff --git a/sust.c b/sust.c
index c836b2a..d684930 100644
--- a/sust.c
+++ b/sust.c
@@ -11,7 +11,7 @@ void sust_init( struct sust * sust ) {
     sust->start_idx = 0;
     sust->idx = 0;
 
-    sust->buf_len = 12800;
+    sust->buf_len = 51200;
     sust->record_buf = malloc( sizeof(float) * sust->buf_len );
     sust->play_buf = malloc( sizeof(float) * sust->buf_len );
 }
@@ -30,6 +30,13 @@ float softcos( float x ) {
     return sin( x * (3.141 / 2.0) );
 }
 
+void sust_resize( struct sust * sust, size_t new_len ) {
+  sust->buf_len = new_len;
+  sust->play_buf = realloc( sust->play_buf, sizeof(float) * new_len );
+  sust->record_buf = realloc( sust->record_buf, sizeof(float) * new_len );
+  sust->idx %= new_len;
+}
+
 void sust_swap(
     struct sust * sust
 ) {
diff --git a/sust.h b/sust.h
index 23c6f67..92bece8 100644
--- a/sust.h
+++ b/sust.h
@@ -21,6 +21,7 @@ struct sust {
 
 
 void sust_init( struct sust * sust );
+void sust_resize( struct sust * sust, size_t new_len );
 void sust_swap( struct sust * sust );
 
 void sust_process(