diff --git a/embassy-stm32/build.rs b/embassy-stm32/build.rs
index 09f940d29..30c525521 100644
--- a/embassy-stm32/build.rs
+++ b/embassy-stm32/build.rs
@@ -714,6 +714,16 @@ fn main() {
     // Generate RCC
     clock_gen.clock_names.insert("sys".to_string());
     clock_gen.clock_names.insert("rtc".to_string());
+
+    // STM32F4 SPI in I2S mode receives a clock input from the dedicated I2S PLL.
+    // For this, there is an additional clock MUX, which is not present in other
+    // peripherals and does not fit the current RCC structure of stm32-data.
+    if chip_name.starts_with("stm32f4") && !chip_name.starts_with("stm32f410") {
+        clock_gen.clock_names.insert("plli2s1_p".to_string());
+        clock_gen.clock_names.insert("plli2s1_q".to_string());
+        clock_gen.clock_names.insert("plli2s1_r".to_string());
+    }
+
     let clock_idents: Vec<_> = clock_gen.clock_names.iter().map(|n| format_ident!("{}", n)).collect();
     g.extend(quote! {
         #[derive(Clone, Copy, Debug)]
diff --git a/embassy-stm32/src/i2s.rs b/embassy-stm32/src/i2s.rs
index 79d6279f6..ce166d718 100644
--- a/embassy-stm32/src/i2s.rs
+++ b/embassy-stm32/src/i2s.rs
@@ -458,7 +458,7 @@ impl<'d, W: Word> I2S<'d, W> {
 
     /// Write data directly to the raw I2S ringbuffer.
     /// This can be used to fill the buffer before starting the DMA transfer.
-    pub async fn write_immediate(&mut self, data: &mut [W]) -> Result<(usize, usize), Error> {
+    pub async fn write_immediate(&mut self, data: &[W]) -> Result<(usize, usize), Error> {
         match &mut self.tx_ring_buffer {
             Some(ring) => Ok(ring.write_immediate(data)?),
             _ => return Err(Error::NotATransmitter),
@@ -491,10 +491,9 @@ impl<'d, W: Word> I2S<'d, W> {
 
         let regs = T::info().regs;
 
-        // TODO move i2s to the new mux infra.
-        //#[cfg(all(rcc_f4, not(stm32f410)))]
-        //let pclk = unsafe { get_freqs() }.plli2s1_q.unwrap();
-        //#[cfg(stm32f410)]
+        #[cfg(all(rcc_f4, not(stm32f410)))]
+        let pclk = unsafe { crate::rcc::get_freqs() }.plli2s1_r.to_hertz().unwrap();
+        #[cfg(not(all(rcc_f4, not(stm32f410))))]
         let pclk = T::frequency();
 
         let (odd, div) = compute_baud_rate(pclk, freq, config.master_clock, config.format);