diff --git a/src/audio_mixer.c b/src/audio_mixer.c
index 835fe6b..f3c9ac4 100644
--- a/src/audio_mixer.c
+++ b/src/audio_mixer.c
@@ -666,19 +666,21 @@ void mixer_init(void)
 
 int mixer_get_numof(void)
 {
-	return nr_mixers;
+	// Return the number of mixers specified in System40.ini, even if
+	// xsystem4 added more mixers.
+	return config.mixer_nr_channels;
 }
 
 const char *mixer_get_name(int n)
 {
-	if (n < 0 || n >= nr_mixers)
+	if (n < 0 || n >= config.mixer_nr_channels)
 		return NULL;
 	return mixers[n].name;
 }
 
 int mixer_set_name(int n, const char *name)
 {
-	if (n < 0 || n >= nr_mixers)
+	if (n < 0 || n >= config.mixer_nr_channels)
 		return 0;
 	free(mixers[n].name);
 	mixers[n].name = strdup(name);
@@ -687,7 +689,7 @@ int mixer_set_name(int n, const char *name)
 
 int mixer_get_volume(int n, int *volume)
 {
-	if (n < 0 || n >= nr_mixers) {
+	if (n < 0 || n >= config.mixer_nr_channels) {
 		return 0;
 	}
 	SDL_LockAudioDevice(audio_device);
@@ -698,7 +700,7 @@ int mixer_get_volume(int n, int *volume)
 
 int mixer_set_volume(int n, int volume)
 {
-	if (n < 0 || n >= nr_mixers)
+	if (n < 0 || n >= config.mixer_nr_channels)
 		return 0;
 	SDL_LockAudioDevice(audio_device);
 	mixers[n].mixer.gain = clamp(0.0f, 1.0f, (float)volume / 100.0f);
@@ -707,7 +709,7 @@ int mixer_set_volume(int n, int volume)
 }
 int mixer_get_mute(int n, int *mute)
 {
-	if (n < 0 || n >= nr_mixers)
+	if (n < 0 || n >= config.mixer_nr_channels)
 		return 0;
 	*mute = mixers[n].muted;
 	return 1;
@@ -715,7 +717,7 @@ int mixer_get_mute(int n, int *mute)
 
 int mixer_set_mute(int n, int mute)
 {
-	if (n < 0 || n >= nr_mixers)
+	if (n < 0 || n >= config.mixer_nr_channels)
 		return 0;
 	mixers[n].muted = !!mute;
 	return 1;