diff --git a/embassy-stm32/src/adc/f3.rs b/embassy-stm32/src/adc/f3.rs
index 2971ad527..b39d6ac8e 100644
--- a/embassy-stm32/src/adc/f3.rs
+++ b/embassy-stm32/src/adc/f3.rs
@@ -50,7 +50,7 @@ impl<'d, T: Instance> Adc<'d, T> {
         while T::regs().cr().read().adcal() {}
 
         // Wait more than 4 clock cycles after adcal is cleared (RM0364 p. 223)
-        delay.delay_us(6 * 1_000_000 / Self::freq().0);
+        delay.delay_us(1 + (6 * 1_000_000 / Self::freq().0));
 
         // Enable the adc
         T::regs().cr().modify(|w| w.set_aden(true));