diff --git a/embassy-stm32/src/rcc/l1.rs b/embassy-stm32/src/rcc/l1.rs
index 517869ca..e6518444 100644
--- a/embassy-stm32/src/rcc/l1.rs
+++ b/embassy-stm32/src/rcc/l1.rs
@@ -1,5 +1,5 @@
 use crate::pac::rcc::vals::{Hpre, Msirange, Plldiv, Pllmul, Pllsrc, Ppre, Sw};
-use crate::pac::RCC;
+use crate::pac::{FLASH, RCC};
 use crate::rcc::{set_freqs, Clocks};
 use crate::time::Hertz;
 use crate::time::U32Ext;
@@ -274,6 +274,13 @@ pub(crate) unsafe fn init(config: Config) {
         }
     };
 
+    // Set flash 64-bit access, prefetch and wait states
+    if sys_clk >= 16_000_000 {
+        FLASH.acr().write(|w| w.set_acc64(true));
+        FLASH.acr().modify(|w| w.set_prften(true));
+        FLASH.acr().modify(|w| w.set_latency(true));
+    }
+
     RCC.cfgr().modify(|w| {
         w.set_sw(sw);
         w.set_hpre(config.ahb_pre.into());
diff --git a/stm32-data b/stm32-data
index c66033b9..97877b42 160000
--- a/stm32-data
+++ b/stm32-data
@@ -1 +1 @@
-Subproject commit c66033b9d220ce6d148a4c90f72acd1118861bb1
+Subproject commit 97877b42a7b14e753dcb3153221dc1f3865070d1