diff --git a/src/include/86box/pit.h b/src/include/86box/pit.h
index d9bce667d..ed60cfa29 100644
--- a/src/include/86box/pit.h
+++ b/src/include/86box/pit.h
@@ -71,6 +71,9 @@ typedef struct PIT {
     ctr_t counters[3];
 
     uint8_t ctrl;
+
+    uint64_t   pit_const;
+
     void *dev_priv;
 } pit_t;
 
@@ -97,6 +100,7 @@ typedef struct pit_intf_t {
     /* Sets a counter's load count handler. */
     void (*set_load_func)(void *data, int counter_id, void (*func)(uint8_t new_m, int new_count));
     void (*ctr_clock)(void *data, int counter_id);
+    void (*set_pit_const)(void *data, uint64_t pit_const);
     void *data;
 } pit_intf_t;
 
@@ -108,6 +112,7 @@ extern double PCICLK;
 extern double AGPCLK;
 
 extern uint64_t PITCONST;
+extern uint64_t PAS16CONST;
 extern uint64_t ISACONST;
 extern uint64_t CGACONST;
 extern uint64_t MDACONST;
@@ -118,6 +123,10 @@ extern uint64_t RTCCONST;
 
 extern int refresh_at_enable;
 
+extern void pit_change_pas16_const(double prescale);
+
+extern void pit_set_pit_const(void *data, uint64_t pit_const);
+
 /* Sets a counter's CLOCK input. */
 extern void pit_ctr_set_clock(ctr_t *ctr, int clock, void *priv);
 
diff --git a/src/include/86box/pit_fast.h b/src/include/86box/pit_fast.h
index 845105185..2a8181a94 100644
--- a/src/include/86box/pit_fast.h
+++ b/src/include/86box/pit_fast.h
@@ -56,6 +56,9 @@ typedef struct ctrf_t {
     };
 
     uint32_t   l;
+
+    uint64_t   pit_const;
+
     pc_timer_t timer;
 
     void (*load_func)(uint8_t new_m, int new_count);
@@ -70,6 +73,8 @@ typedef struct pitf_t {
     uint8_t ctrl;
 } pitf_t;
 
+extern void pitf_set_pit_const(void *data, uint64_t pit_const);
+
 extern uint8_t pitf_read_reg(void *priv, uint8_t reg);
 
 extern const pit_intf_t pit_fast_intf;
diff --git a/src/pit.c b/src/pit.c
index 20baf3f66..7ab48bbd8 100644
--- a/src/pit.c
+++ b/src/pit.c
@@ -47,6 +47,7 @@ pit_intf_t pit_devs[2];
 
 double cpuclock;
 double PITCONSTD;
+double PAS16CONSTD;
 double SYSCLK;
 double isa_timing;
 double bus_timing;
@@ -56,6 +57,7 @@ double PCICLK;
 double AGPCLK;
 
 uint64_t PITCONST;
+uint64_t PAS16CONST;
 uint64_t ISACONST;
 uint64_t CGACONST;
 uint64_t MDACONST;
@@ -523,7 +525,7 @@ pit_timer_over(void *priv)
     for (uint8_t i = 0; i < 3; i++)
         pit_ctr_set_clock_common(&dev->counters[i], dev->clock, dev);
 
-    timer_advance_u64(&dev->callback_timer, PITCONST >> 1ULL);
+    timer_advance_u64(&dev->callback_timer, dev->pit_const >> 1ULL);
 }
 
 static void
@@ -873,6 +875,20 @@ pit_handler(int set, uint16_t base, int size, void *priv)
     io_handler(set, base, size, pit_read, NULL, NULL, pit_write, NULL, NULL, priv);
 }
 
+void
+pit_set_pit_const(void *data, uint64_t pit_const)
+{
+    pit_t *pit = (pit_t *) data;
+
+    pit->pit_const = pit_const;
+}
+
+static void
+pit_speed_changed(void *priv)
+{
+    pit_set_pit_const(priv, PITCONST);
+}
+
 static void
 pit_close(void *priv)
 {
@@ -896,7 +912,7 @@ pit_init(const device_t *info)
 
     if (!(dev->flags & PIT_PS2) && !(dev->flags & PIT_CUSTOM_CLOCK)) {
         timer_add(&dev->callback_timer, pit_timer_over, (void *) dev, 0);
-        timer_set_delay_u64(&dev->callback_timer, PITCONST >> 1ULL);
+        timer_set_delay_u64(&dev->callback_timer, dev->pit_const >> 1ULL);
     }
 
     dev->flags = info->local;
@@ -919,7 +935,7 @@ const device_t i8253_device = {
     .close         = pit_close,
     .reset         = NULL,
     { .available = NULL },
-    .speed_changed = NULL,
+    .speed_changed = pit_speed_changed,
     .force_redraw  = NULL,
     .config        = NULL
 };
@@ -947,7 +963,7 @@ const device_t i8254_device = {
     .close         = pit_close,
     .reset         = NULL,
     { .available = NULL },
-    .speed_changed = NULL,
+    .speed_changed = pit_speed_changed,
     .force_redraw  = NULL,
     .config        = NULL
 };
@@ -961,7 +977,7 @@ const device_t i8254_sec_device = {
     .close         = pit_close,
     .reset         = NULL,
     { .available = NULL },
-    .speed_changed = NULL,
+    .speed_changed = pit_speed_changed,
     .force_redraw  = NULL,
     .config        = NULL
 };
@@ -989,7 +1005,7 @@ const device_t i8254_ps2_device = {
     .close         = pit_close,
     .reset         = NULL,
     { .available = NULL },
-    .speed_changed = NULL,
+    .speed_changed = pit_speed_changed,
     .force_redraw  = NULL,
     .config        = NULL
 };
@@ -1074,6 +1090,12 @@ pit_ps2_init(int type)
     return pit;
 }
 
+void
+pit_change_pas16_const(double prescale)
+{
+    PAS16CONST  = (uint64_t) ((PITCONSTD / prescale) * (double) (1ULL << 32));
+}
+
 void
 pit_set_clock(uint32_t clock)
 {
@@ -1169,6 +1191,9 @@ pit_set_clock(uint32_t clock)
 
     TIMER_USEC = (uint64_t) ((cpuclock / 1000000.0) * (double) (1ULL << 32));
 
+    PAS16CONSTD = (cpuclock / 441000.0);
+    PAS16CONST  = (uint64_t) (PITCONSTD * (double) (1ULL << 32));
+
     isa_timing = (cpuclock / (double) cpu_isa_speed);
     if (cpu_64bitbus)
         bus_timing = (cpuclock / (cpu_busspeed / 2));
@@ -1200,5 +1225,6 @@ const pit_intf_t pit_classic_intf = {
     &pit_ctr_set_out_func,
     &pit_ctr_set_load_func,
     &ctr_clock,
+    &pit_set_pit_const,
     NULL,
 };
diff --git a/src/pit_fast.c b/src/pit_fast.c
index 9c5d622ec..0a7e1db09 100644
--- a/src/pit_fast.c
+++ b/src/pit_fast.c
@@ -126,7 +126,7 @@ static int
 pitf_read_timer(ctrf_t *ctr)
 {
     if (ctr->using_timer && !(ctr->m == 3 && !ctr->gate) && timer_is_enabled(&ctr->timer)) {
-        int read = (int) ((timer_get_remaining_u64(&ctr->timer)) / PITCONST);
+        int read = (int) ((timer_get_remaining_u64(&ctr->timer)) / ctr->pit_const);
         if (ctr->m == 2)
             read++;
         if (read < 0)
@@ -168,7 +168,7 @@ pitf_ctr_load(ctrf_t *ctr, void *priv)
         case 0: /*Interrupt on terminal count*/
             ctr->count = l;
             if (ctr->using_timer)
-                timer_set_delay_u64(&ctr->timer, (uint64_t) (l * PITCONST));
+                timer_set_delay_u64(&ctr->timer, (uint64_t) (l * ctr->pit_const));
             pitf_ctr_set_out(ctr, 0, pit);
             ctr->thit    = 0;
             ctr->enabled = ctr->gate;
@@ -180,7 +180,7 @@ pitf_ctr_load(ctrf_t *ctr, void *priv)
             if (ctr->initial) {
                 ctr->count = l - 1;
                 if (ctr->using_timer)
-                    timer_set_delay_u64(&ctr->timer, (uint64_t) ((l - 1) * PITCONST));
+                    timer_set_delay_u64(&ctr->timer, (uint64_t) ((l - 1) * ctr->pit_const));
                 pitf_ctr_set_out(ctr, 1, pit);
                 ctr->thit = 0;
             }
@@ -190,7 +190,7 @@ pitf_ctr_load(ctrf_t *ctr, void *priv)
             if (ctr->initial) {
                 ctr->count = l;
                 if (ctr->using_timer)
-                    timer_set_delay_u64(&ctr->timer, (uint64_t) (((l + 1) >> 1) * PITCONST));
+                    timer_set_delay_u64(&ctr->timer, (uint64_t) (((l + 1) >> 1) * ctr->pit_const));
                 pitf_ctr_set_out(ctr, 1, pit);
                 ctr->thit = 0;
             }
@@ -202,7 +202,7 @@ pitf_ctr_load(ctrf_t *ctr, void *priv)
             else {
                 ctr->count = l;
                 if (ctr->using_timer)
-                    timer_set_delay_u64(&ctr->timer, (uint64_t) (l * PITCONST));
+                    timer_set_delay_u64(&ctr->timer, (uint64_t) (l * ctr->pit_const));
                 pitf_ctr_set_out(ctr, 0, pit);
                 ctr->thit = 0;
             }
@@ -240,7 +240,7 @@ pitf_set_gate_no_timer(ctrf_t *ctr, int gate, void *priv)
         case 0: /*Interrupt on terminal count*/
         case 4: /*Software triggered stobe*/
             if (ctr->using_timer && !ctr->running)
-                timer_set_delay_u64(&ctr->timer, (uint64_t) (l * PITCONST));
+                timer_set_delay_u64(&ctr->timer, (uint64_t) (l * ctr->pit_const));
             ctr->enabled = gate;
             break;
         case 1: /*Hardware retriggerable one-shot*/
@@ -248,7 +248,7 @@ pitf_set_gate_no_timer(ctrf_t *ctr, int gate, void *priv)
             if (gate && !ctr->gate) {
                 ctr->count = l;
                 if (ctr->using_timer)
-                    timer_set_delay_u64(&ctr->timer, (uint64_t) (l * PITCONST));
+                    timer_set_delay_u64(&ctr->timer, (uint64_t) (l * ctr->pit_const));
                 pitf_ctr_set_out(ctr, 0, pit);
                 ctr->thit    = 0;
                 ctr->enabled = 1;
@@ -258,7 +258,7 @@ pitf_set_gate_no_timer(ctrf_t *ctr, int gate, void *priv)
             if (gate && !ctr->gate) {
                 ctr->count = l - 1;
                 if (ctr->using_timer)
-                    timer_set_delay_u64(&ctr->timer, (uint64_t) (l * PITCONST));
+                    timer_set_delay_u64(&ctr->timer, (uint64_t) (l * ctr->pit_const));
                 pitf_ctr_set_out(ctr, 1, pit);
                 ctr->thit = 0;
             }
@@ -268,7 +268,7 @@ pitf_set_gate_no_timer(ctrf_t *ctr, int gate, void *priv)
             if (gate && !ctr->gate) {
                 ctr->count = l;
                 if (ctr->using_timer)
-                    timer_set_delay_u64(&ctr->timer, (uint64_t) (((l + 1) >> 1) * PITCONST));
+                    timer_set_delay_u64(&ctr->timer, (uint64_t) (((l + 1) >> 1) * ctr->pit_const));
                 pitf_ctr_set_out(ctr, 1, pit);
                 ctr->thit = 0;
             }
@@ -306,7 +306,7 @@ pitf_over(ctrf_t *ctr, void *priv)
     if (ctr->disabled) {
         ctr->count += 0xffff;
         if (ctr->using_timer)
-            timer_advance_u64(&ctr->timer, (uint64_t) (0xffff * PITCONST));
+            timer_advance_u64(&ctr->timer, (uint64_t) (0xffff * ctr->pit_const));
         return;
     }
 
@@ -318,12 +318,12 @@ pitf_over(ctrf_t *ctr, void *priv)
             ctr->thit = 1;
             ctr->count += 0xffff;
             if (ctr->using_timer)
-                timer_advance_u64(&ctr->timer, (uint64_t) (0xffff * PITCONST));
+                timer_advance_u64(&ctr->timer, (uint64_t) (0xffff * ctr->pit_const));
             break;
         case 2: /*Rate generator*/
             ctr->count += l;
             if (ctr->using_timer)
-                timer_advance_u64(&ctr->timer, (uint64_t) (l * PITCONST));
+                timer_advance_u64(&ctr->timer, (uint64_t) (l * ctr->pit_const));
             pitf_ctr_set_out(ctr, 0, pit);
             pitf_ctr_set_out(ctr, 1, pit);
             break;
@@ -332,16 +332,16 @@ pitf_over(ctrf_t *ctr, void *priv)
                 pitf_ctr_set_out(ctr, 0, pit);
                 ctr->count += (l >> 1);
                 if (ctr->using_timer)
-                    timer_advance_u64(&ctr->timer, (uint64_t) ((l >> 1) * PITCONST));
+                    timer_advance_u64(&ctr->timer, (uint64_t) ((l >> 1) * ctr->pit_const));
             } else {
                 pitf_ctr_set_out(ctr, 1, pit);
                 ctr->count += ((l + 1) >> 1);
                 if (ctr->using_timer)
-                    timer_advance_u64(&ctr->timer, (uint64_t) (((l + 1) >> 1) * PITCONST));
+                    timer_advance_u64(&ctr->timer, (uint64_t) (((l + 1) >> 1) * ctr->pit_const));
             }
 #if 0
             if (!t)
-                pclog("pit_over: square wave mode c=%x  %lli  %f\n", pit.c[t], tsc, PITCONST);
+                pclog("pit_over: square wave mode c=%x  %lli  %f\n", pit.c[t], tsc, ctr->pit_const);
 #endif
             break;
         case 4: /*Software triggered strove*/
@@ -353,12 +353,12 @@ pitf_over(ctrf_t *ctr, void *priv)
                 ctr->newcount = 0;
                 ctr->count += l;
                 if (ctr->using_timer)
-                    timer_advance_u64(&ctr->timer, (uint64_t) (l * PITCONST));
+                    timer_advance_u64(&ctr->timer, (uint64_t) (l * ctr->pit_const));
             } else {
                 ctr->thit = 1;
                 ctr->count += 0xffff;
                 if (ctr->using_timer)
-                    timer_advance_u64(&ctr->timer, (uint64_t) (0xffff * PITCONST));
+                    timer_advance_u64(&ctr->timer, (uint64_t) (0xffff * ctr->pit_const));
             }
             break;
         case 5: /*Hardware triggered strove*/
@@ -369,7 +369,7 @@ pitf_over(ctrf_t *ctr, void *priv)
             ctr->thit = 1;
             ctr->count += 0xffff;
             if (ctr->using_timer)
-                timer_advance_u64(&ctr->timer, (uint64_t) (0xffff * PITCONST));
+                timer_advance_u64(&ctr->timer, (uint64_t) (0xffff * ctr->pit_const));
             break;
 
         default:
@@ -659,6 +659,24 @@ pitf_reset(pitf_t *dev)
     dev->counters[2].gate = 0;
 }
 
+void
+pitf_set_pit_const(void *data, uint64_t pit_const)
+{
+    pitf_t *pit = (pitf_t *) data;
+    ctrf_t *ctr;
+
+    for (uint8_t i = 0; i < 3; i++) {
+        ctr = &pit->counters[i];
+        ctr->pit_const = pit_const;
+    }
+}
+
+static void
+pitf_speed_changed(void *priv)
+{
+    pitf_set_pit_const(priv, PITCONST);
+}
+
 static void
 pitf_close(void *priv)
 {
@@ -707,7 +725,7 @@ const device_t i8253_fast_device = {
     .close         = pitf_close,
     .reset         = NULL,
     { .available = NULL },
-    .speed_changed = NULL,
+    .speed_changed = pitf_speed_changed,
     .force_redraw  = NULL,
     .config        = NULL
 };
@@ -721,7 +739,7 @@ const device_t i8254_fast_device = {
     .close         = pitf_close,
     .reset         = NULL,
     { .available = NULL },
-    .speed_changed = NULL,
+    .speed_changed = pitf_speed_changed,
     .force_redraw  = NULL,
     .config        = NULL
 };
@@ -735,7 +753,7 @@ const device_t i8254_sec_fast_device = {
     .close         = pitf_close,
     .reset         = NULL,
     { .available = NULL },
-    .speed_changed = NULL,
+    .speed_changed = pitf_speed_changed,
     .force_redraw  = NULL,
     .config        = NULL
 };
@@ -763,7 +781,7 @@ const device_t i8254_ps2_fast_device = {
     .close         = pitf_close,
     .reset         = NULL,
     { .available = NULL },
-    .speed_changed = NULL,
+    .speed_changed = pitf_speed_changed,
     .force_redraw  = NULL,
     .config        = NULL
 };
@@ -777,5 +795,6 @@ const pit_intf_t pit_fast_intf = {
     &pitf_ctr_set_out_func,
     &pitf_ctr_set_load_func,
     &pitf_ctr_clock,
+    &pitf_set_pit_const,
     NULL,
 };
diff --git a/src/sound/snd_pas16.c b/src/sound/snd_pas16.c
index d8187cf0f..45a18ff73 100644
--- a/src/sound/snd_pas16.c
+++ b/src/sound/snd_pas16.c
@@ -354,7 +354,6 @@ static void
 pas16_out(uint16_t port, uint8_t val, void *priv)
 {
     pas16_t *pas16 = (pas16_t *) priv;
-    pit_t *pit = (pit_t *) pas16->pit;
     pas16_log("pas16_out : port %04X val %02X  %04X:%04X\n", port, val, CS, cpu_state.pc);
     switch (port) {
         case 0x388:
@@ -728,6 +727,28 @@ pas16_get_music_buffer(int32_t *buffer, int len, void *priv)
     pas16->opl.reset_buffer(pas16->opl.priv);
 }
 
+static void
+pas16_speed_changed(void *priv)
+{
+    pas16_t *pas16 = (pas16_t *) priv;
+
+    /* TODO: In PAS16 mode:
+        pit_change_pas16_const(prescale);
+        pit_set_pit_const(pas16->pit, PAS16CONST);
+     */
+
+    pit_set_pit_const(pas16->pit, PITCONST);
+}
+
+static void
+pas16_reset(void *priv)
+{
+    pas16_t *pas16 = (pas16_t *) priv;
+
+    /* TODO: Reset the entire PAS16 state here. */
+    pit_set_pit_const(pas16->pit, PITCONST);
+}
+
 static void *
 pas16_init(UNUSED(const device_t *info))
 {
@@ -743,6 +764,7 @@ pas16_init(UNUSED(const device_t *info))
     sb_dsp_set_mpu(&pas16->dsp, pas16->mpu);
 
     pas16->pit = device_add(&i8254_ext_io_device);
+    pit_set_pit_const(pas16->pit, PITCONST);
     pas16->pit->dev_priv = pas16;
     pas16->irq = 10;
     pas16->dma = 3;
@@ -798,9 +820,9 @@ const device_t pas16_device = {
     .local         = 0,
     .init          = pas16_init,
     .close         = pas16_close,
-    .reset         = NULL,
+    .reset         = pas16_reset,
     { .available = NULL },
-    .speed_changed = NULL,
+    .speed_changed = pas16_speed_changed,
     .force_redraw  = NULL,
     .config        = pas16_config
 };