diff --git a/src/mod/applications/mod_conference/mod_conference.c b/src/mod/applications/mod_conference/mod_conference.c
index dcb03eec33..332857fc83 100644
--- a/src/mod/applications/mod_conference/mod_conference.c
+++ b/src/mod/applications/mod_conference/mod_conference.c
@@ -425,6 +425,7 @@ void *SWITCH_THREAD_FUNC conference_thread_run(switch_thread_t *thread, void *ob
 			}
 		}
 
+		switch_mutex_lock(conference->file_mutex);
 		/* If a file or speech event is being played */
 		if (conference->fnode && !switch_test_flag(conference->fnode, NFLAG_PAUSE)) {
 			/* Lead in time */
@@ -531,6 +532,7 @@ void *SWITCH_THREAD_FUNC conference_thread_run(switch_thread_t *thread, void *ob
 				}
 			}
 		}
+		switch_mutex_lock(conference->file_mutex);
 
 		if (ready || has_file_data) {
 			/* Use more bits in the main_frame to preserve the exact sum of the audio samples. */