diff --git a/embassy-stm32/src/rcc/f1.rs b/embassy-stm32/src/rcc/f1.rs
index e667dbf90..1c14429fc 100644
--- a/embassy-stm32/src/rcc/f1.rs
+++ b/embassy-stm32/src/rcc/f1.rs
@@ -24,10 +24,15 @@ pub struct Config {
     pub pclk1: Option<Hertz>,
     pub pclk2: Option<Hertz>,
     pub adcclk: Option<Hertz>,
+    pub pllxtpre: Option<bool>,
 }
 
 pub(crate) unsafe fn init(config: Config) {
-    let pllsrcclk = config.hse.map(|hse| hse.0).unwrap_or(HSI_FREQ.0 / 2);
+    let pllsrcclk = config.hse.map(|hse| hse.0 / match config.pllxtpre {
+        Some(b) => if b {2} else {1},
+        None => {1},
+    }).unwrap_or(HSI_FREQ.0 / 2);
+
     let sysclk = config.sys_ck.map(|sys| sys.0).unwrap_or(pllsrcclk);
     let pllmul = sysclk / pllsrcclk;
 
@@ -143,6 +148,7 @@ pub(crate) unsafe fn init(config: Config) {
     }
 
     if let Some(pllmul_bits) = pllmul_bits {
+        RCC.cfgr().modify(|w| w.set_pllxtpre(Pllxtpre(config.pllxtpre.is_some() as u8)));
         // enable PLL and wait for it to be ready
         RCC.cfgr().modify(|w| {
             w.set_pllmul(Pllmul(pllmul_bits));