add missing NULL check

diff --git a/libs/ardour/disk_reader.cc b/libs/ardour/disk_reader.cc
index 42986f7fa452bcc12fa7502babf314fbb346003e..c86cc7680f251320501ad731ce9ce1ada6014881 100644 (file)
--- a/libs/ardour/disk_reader.cc
+++ b/libs/ardour/disk_reader.cc
@@ -782,7 +782,7 @@ DiskReader::refill (Sample* sum_buffer, Sample* mixdown_buffer, float* gain_buff
                return -1;
        }
 
-       if ((_session.transport_speed() < 0.0f) != rt_midibuffer()->reversed()) {
+       if (rt_midibuffer() && (_session.transport_speed() < 0.0f) != rt_midibuffer()->reversed()) {
                rt_midibuffer()->reverse ();
        }