diff --git a/embassy-stm32/Cargo.toml b/embassy-stm32/Cargo.toml
index 6881f13e8..b2f863377 100644
--- a/embassy-stm32/Cargo.toml
+++ b/embassy-stm32/Cargo.toml
@@ -28,7 +28,6 @@ stm32-metapac = { version = "0.1.0", path = "../stm32-metapac", features = ["rt"
 vcell = { version = "0.1.3", optional = true }
 bxcan = "0.5.1"
 seq-macro = "0.2.2"
-cast = { version = "0.2.2", default-features = false }
 
 cfg-if = "1.0.0"
 
diff --git a/embassy-stm32/src/rcc/f1/mod.rs b/embassy-stm32/src/rcc/f1/mod.rs
index 75367d421..fc9fc128f 100644
--- a/embassy-stm32/src/rcc/f1/mod.rs
+++ b/embassy-stm32/src/rcc/f1/mod.rs
@@ -1,3 +1,4 @@
+use core::convert::TryFrom;
 use core::marker::PhantomData;
 
 use embassy::util::Unborrow;
@@ -7,8 +8,6 @@ use crate::pac::{FLASH, RCC};
 use crate::peripherals;
 use crate::time::Hertz;
 
-use cast::u32;
-
 use super::{set_freqs, Clocks};
 
 const HSI: u32 = 8_000_000;
@@ -94,8 +93,8 @@ impl<'d> Rcc<'d> {
             })
             .unwrap_or(0b011);
 
-        let ppre1: i32 = 1 << (ppre1_bits - 0b011);
-        let pclk1 = hclk / u32(ppre1).unwrap();
+        let ppre1 = 1 << (ppre1_bits - 0b011);
+        let pclk1 = hclk / u32::try_from(ppre1).unwrap();
         let timer_mul1 = if ppre1 == 1 { 1 } else { 2 };
 
         assert!(pclk1 <= 36_000_000);
@@ -113,8 +112,8 @@ impl<'d> Rcc<'d> {
             })
             .unwrap_or(0b011);
 
-        let ppre2: i32 = 1 << (ppre2_bits - 0b011);
-        let pclk2 = hclk / u32(ppre2).unwrap();
+        let ppre2 = 1 << (ppre2_bits - 0b011);
+        let pclk2 = hclk / u32::try_from(ppre2).unwrap();
         let timer_mul2 = if ppre2 == 1 { 1 } else { 2 };
 
         assert!(pclk2 <= 72_000_000);
@@ -154,7 +153,7 @@ impl<'d> Rcc<'d> {
             .unwrap_or(0b11);
 
         let apre = (apre_bits + 1) << 1;
-        let adcclk = pclk2 / u32(apre);
+        let adcclk = pclk2 / unwrap!(u32::try_from(apre));
 
         assert!(adcclk <= 14_000_000);