diff --git a/platforms/stm32f7/src/f722/board.rs b/platforms/stm32f7/src/f722/board.rs
index c556f00..e2b23cb 100644
--- a/platforms/stm32f7/src/f722/board.rs
+++ b/platforms/stm32f7/src/f722/board.rs
@@ -206,6 +206,13 @@ fn initialize_icm42688(
     configure_spi3_pins_pc10_pc11_pc12(&device.RCC, &device.GPIOC);
     configure_exti3_pin_pc3(&device.GPIOC);
     configure_exti3(&device.RCC, device.SYSCFG, device.EXTI);
+    // PA2/PA3 writes take effect only after enabling the GPIOA bus clock.
+    // The ICM route enables GPIOA later for chip select, which is too late for
+    // the USART2 alternate-function configuration below.
+    device
+        .RCC
+        .ahb1enr()
+        .modify(|_, write| write.gpioaen().set_bit());
     configure_usart2_pins_pa2_pa3(&device.GPIOA);
     configure_vertical_pins(&device.RCC, &device.GPIOA, &device.GPIOB, vertical);