diff --git a/hw/arm/netduino2.c b/hw/arm/netduino2.c
index 79e19392b5..8f10334144 100644
--- a/hw/arm/netduino2.c
+++ b/hw/arm/netduino2.c
@@ -30,10 +30,20 @@
 #include "hw/arm/stm32f205_soc.h"
 #include "hw/arm/boot.h"
 
+/* Main SYSCLK frequency in Hz (120MHz) */
+#define SYSCLK_FRQ 120000000ULL
+
 static void netduino2_init(MachineState *machine)
 {
     DeviceState *dev;
 
+    /*
+     * TODO: ideally we would model the SoC RCC and let it handle
+     * system_clock_scale, including its ability to define different
+     * possible SYSCLK sources.
+     */
+    system_clock_scale = NANOSECONDS_PER_SECOND / SYSCLK_FRQ;
+
     dev = qdev_new(TYPE_STM32F205_SOC);
     qdev_prop_set_string(dev, "cpu-type", ARM_CPU_TYPE_NAME("cortex-m3"));
     sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
diff --git a/hw/arm/netduinoplus2.c b/hw/arm/netduinoplus2.c
index 958d21dd9f..68abd3ec69 100644
--- a/hw/arm/netduinoplus2.c
+++ b/hw/arm/netduinoplus2.c
@@ -30,10 +30,20 @@
 #include "hw/arm/stm32f405_soc.h"
 #include "hw/arm/boot.h"
 
+/* Main SYSCLK frequency in Hz (168MHz) */
+#define SYSCLK_FRQ 168000000ULL
+
 static void netduinoplus2_init(MachineState *machine)
 {
     DeviceState *dev;
 
+    /*
+     * TODO: ideally we would model the SoC RCC and let it handle
+     * system_clock_scale, including its ability to define different
+     * possible SYSCLK sources.
+     */
+    system_clock_scale = NANOSECONDS_PER_SECOND / SYSCLK_FRQ;
+
     dev = qdev_new(TYPE_STM32F405_SOC);
     qdev_prop_set_string(dev, "cpu-type", ARM_CPU_TYPE_NAME("cortex-m4"));
     sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);