diff --git a/src/output_init.c b/src/output_init.c
index 51fe36c47..3b8a7a9f1 100644
--- a/src/output_init.c
+++ b/src/output_init.c
@@ -213,6 +213,8 @@ ao_base_init(struct audio_output *ao,
 	ao->cond = g_cond_new();
 
 	ao->mixer = NULL;
+	ao->replay_gain_filter = NULL;
+	ao->other_replay_gain_filter = NULL;
 
 	/* the "convert" filter must be the last one in the chain */