diff --git a/fftools/ffmpeg_mux_init.c b/fftools/ffmpeg_mux_init.c
index 818d76acda..d3d7d022ff 100644
--- a/fftools/ffmpeg_mux_init.c
+++ b/fftools/ffmpeg_mux_init.c
@@ -832,6 +832,7 @@ static int new_stream_audio(Muxer *mux, const OptionsContext *o,
         int channels = 0;
         char *layout = NULL;
         char *sample_fmt = NULL;
+        const char *apad = NULL;
 
         MATCH_PER_STREAM_OPT(audio_channels, i, channels, oc, st);
         if (channels) {
@@ -854,8 +855,12 @@ static int new_stream_audio(Muxer *mux, const OptionsContext *o,
 
         MATCH_PER_STREAM_OPT(audio_sample_rate, i, audio_enc->sample_rate, oc, st);
 
-        MATCH_PER_STREAM_OPT(apad, str, ost->apad, oc, st);
-        ost->apad = av_strdup(ost->apad);
+        MATCH_PER_STREAM_OPT(apad, str, apad, oc, st);
+        if (apad) {
+            ost->apad = av_strdup(apad);
+            if (!ost->apad)
+                return AVERROR(ENOMEM);
+        }
     }
 
     return 0;