diff --git a/hw/arm/mps2-tz.c b/hw/arm/mps2-tz.c
index 72da8cb1a1..85e80c4d72 100644
--- a/hw/arm/mps2-tz.c
+++ b/hw/arm/mps2-tz.c
@@ -111,6 +111,7 @@ struct MPS2TZMachineClass {
     uint32_t fpgaio_num_leds; /* Number of LEDs in FPGAIO LED0 register */
     bool fpgaio_has_switches; /* Does FPGAIO have SWITCH register? */
     int numirq; /* Number of external interrupts */
+    int uart_overflow_irq; /* number of the combined UART overflow IRQ */
     const RAMInfo *raminfo;
     const char *armsse_type;
 };
@@ -770,7 +771,7 @@ static void mps2tz_common_init(MachineState *machine)
                             &error_fatal);
     qdev_realize(DEVICE(&mms->uart_irq_orgate), NULL, &error_fatal);
     qdev_connect_gpio_out(DEVICE(&mms->uart_irq_orgate), 0,
-                          get_sse_irq_in(mms, 47));
+                          get_sse_irq_in(mms, mmc->uart_overflow_irq));
 
     /* Most of the devices in the FPGA are behind Peripheral Protection
      * Controllers. The required order for initializing things is:
@@ -1046,6 +1047,7 @@ static void mps2tz_an505_class_init(ObjectClass *oc, void *data)
     mmc->fpgaio_num_leds = 2;
     mmc->fpgaio_has_switches = false;
     mmc->numirq = 92;
+    mmc->uart_overflow_irq = 47;
     mmc->raminfo = an505_raminfo;
     mmc->armsse_type = TYPE_IOTKIT;
     mps2tz_set_default_ram_info(mmc);
@@ -1069,6 +1071,7 @@ static void mps2tz_an521_class_init(ObjectClass *oc, void *data)
     mmc->fpgaio_num_leds = 2;
     mmc->fpgaio_has_switches = false;
     mmc->numirq = 92;
+    mmc->uart_overflow_irq = 47;
     mmc->raminfo = an505_raminfo; /* AN521 is the same as AN505 here */
     mmc->armsse_type = TYPE_SSE200;
     mps2tz_set_default_ram_info(mmc);
@@ -1092,6 +1095,7 @@ static void mps3tz_an524_class_init(ObjectClass *oc, void *data)
     mmc->fpgaio_num_leds = 10;
     mmc->fpgaio_has_switches = true;
     mmc->numirq = 95;
+    mmc->uart_overflow_irq = 47;
     mmc->raminfo = an524_raminfo;
     mmc->armsse_type = TYPE_SSE200;
     mps2tz_set_default_ram_info(mmc);