diff --git a/libao2/ao_alsa.c b/libao2/ao_alsa.c
index e13e641d05..5c4c5c585b 100644
--- a/libao2/ao_alsa.c
+++ b/libao2/ao_alsa.c
@@ -326,7 +326,7 @@ static int init(int rate_hz, int channels, int format, int flags)
     snd_pcm_uframes_t chunk_size;
     snd_pcm_uframes_t bufsize;
     snd_pcm_uframes_t boundary;
-    opt_t subopts[] = {
+    const opt_t subopts[] = {
       {"block", OPT_ARG_BOOL, &block, NULL},
       {"device", OPT_ARG_STR, &device, (opt_test_f)str_maxlen},
       {NULL}
diff --git a/libao2/ao_dart.c b/libao2/ao_dart.c
index 6038418203..58ee4d1886 100644
--- a/libao2/ao_dart.c
+++ b/libao2/ao_dart.c
@@ -146,7 +146,7 @@ static int init(int rate, int channels, int format, int flags)
     int nDartSamples = DEFAULT_DART_SAMPLES;
     int nBytesPerSample;
 
-    opt_t subopts[] = {
+    const opt_t subopts[] = {
         {"share", OPT_ARG_BOOL, &fShare, NULL},
         {"bufsize", OPT_ARG_INT, &nDartSamples, (opt_test_f)int_non_neg},
         {NULL}
diff --git a/libao2/ao_dsound.c b/libao2/ao_dsound.c
index 4197c30e27..fc069dad5e 100644
--- a/libao2/ao_dsound.c
+++ b/libao2/ao_dsound.c
@@ -223,7 +223,7 @@ static int InitDirectSound(void)
     HRESULT (WINAPI *OurDirectSoundCreate)(LPGUID, LPDIRECTSOUND *, LPUNKNOWN);
 	HRESULT (WINAPI *OurDirectSoundEnumerate)(LPDSENUMCALLBACKA, LPVOID);
 	int device_index=0;
-	opt_t subopts[] = {
+	const opt_t subopts[] = {
 	  {"device", OPT_ARG_INT, &device_num,NULL},
 	  {NULL}
 	};
diff --git a/libao2/ao_jack.c b/libao2/ao_jack.c
index e92786c28d..7d22ca1676 100644
--- a/libao2/ao_jack.c
+++ b/libao2/ao_jack.c
@@ -208,7 +208,7 @@ static int init(int rate, int channels, int format, int flags) {
   char *port_name = NULL;
   char *client_name = NULL;
   int autostart = 0;
-  opt_t subopts[] = {
+  const opt_t subopts[] = {
     {"port", OPT_ARG_MSTRZ, &port_name, NULL},
     {"name", OPT_ARG_MSTRZ, &client_name, NULL},
     {"estimate", OPT_ARG_BOOL, &estimate, NULL},
diff --git a/libao2/ao_mpegpes.c b/libao2/ao_mpegpes.c
index 64cb05fa03..e05e3b1a53 100644
--- a/libao2/ao_mpegpes.c
+++ b/libao2/ao_mpegpes.c
@@ -158,7 +158,7 @@ static int preinit(const char *arg)
 	int card = -1;
 	char *ao_file = NULL;
 
-	opt_t subopts[] = {
+	const opt_t subopts[] = {
 		{"card", OPT_ARG_INT, &card, NULL},
 		{"file", OPT_ARG_MSTRZ, &ao_file, NULL},
 		{NULL}
diff --git a/libao2/ao_openal.c b/libao2/ao_openal.c
index a5d007f93b..55d5476288 100644
--- a/libao2/ao_openal.c
+++ b/libao2/ao_openal.c
@@ -106,7 +106,7 @@ static int init(int rate, int channels, int format, int flags) {
   ALCint freq = 0;
   ALCint attribs[] = {ALC_FREQUENCY, rate, 0, 0};
   int i;
-  opt_t subopts[] = {
+  const opt_t subopts[] = {
     {NULL}
   };
   if (subopt_parse(ao_subdevice, subopts) != 0) {
diff --git a/libao2/ao_pcm.c b/libao2/ao_pcm.c
index 7f7a6e3b27..9dc97e7554 100644
--- a/libao2/ao_pcm.c
+++ b/libao2/ao_pcm.c
@@ -94,7 +94,7 @@ static int control(int cmd,void *arg){
 // return: 1=success 0=fail
 static int init(int rate,int channels,int format,int flags){
     int bits;
-    opt_t subopts[] = {
+    const opt_t subopts[] = {
         {"waveheader", OPT_ARG_BOOL, &ao_pcm_waveheader, NULL},
         {"file",       OPT_ARG_MSTRZ, &ao_outputfilename, NULL},
         {"fast",       OPT_ARG_BOOL, &fast, NULL},