diff --git a/libs/ardour/ardour/audiosource.h b/libs/ardour/ardour/audiosource.h
index 345d424cf3..59d5add122 100644
--- a/libs/ardour/ardour/audiosource.h
+++ b/libs/ardour/ardour/audiosource.h
@@ -156,6 +156,7 @@ class LIBARDOUR_API AudioSource : virtual public Source,
 	 *  during the handling of the signal.
 	 */
         mutable Glib::Threads::Mutex _peaks_ready_lock;
+        Glib::Threads::Mutex _initialize_peaks_lock;
 
 	int        _peakfile_fd;
 	framecnt_t peak_leftover_cnt;
diff --git a/libs/ardour/audiosource.cc b/libs/ardour/audiosource.cc
index e7d81feaec..9d90d05cb1 100644
--- a/libs/ardour/audiosource.cc
+++ b/libs/ardour/audiosource.cc
@@ -238,6 +238,7 @@ AudioSource::rename_peakfile (string newpath)
 int
 AudioSource::initialize_peakfile (const string& audio_path, const bool in_session)
 {
+	Glib::Threads::Mutex::Lock lm (_initialize_peaks_lock);
 	GStatBuf statbuf;
 
 	_peakpath = construct_peak_filepath (audio_path, in_session);