diff --git a/embassy-stm32/src/flash/f0.rs b/embassy-stm32/src/flash/f0.rs
index d011522b..1ab8435a 100644
--- a/embassy-stm32/src/flash/f0.rs
+++ b/embassy-stm32/src/flash/f0.rs
@@ -19,8 +19,10 @@ pub(crate) unsafe fn lock() {
 }
 
 pub(crate) unsafe fn unlock() {
-    pac::FLASH.keyr().write(|w| w.set_fkeyr(0x4567_0123));
-    pac::FLASH.keyr().write(|w| w.set_fkeyr(0xCDEF_89AB));
+    if pac::FLASH.cr().read().lock() {
+        pac::FLASH.keyr().write(|w| w.set_fkeyr(0x4567_0123));
+        pac::FLASH.keyr().write(|w| w.set_fkeyr(0xCDEF_89AB));
+    }
 }
 
 pub(crate) unsafe fn enable_blocking_write() {
diff --git a/embassy-stm32/src/flash/f3.rs b/embassy-stm32/src/flash/f3.rs
index 065369f6..7e6d7ca2 100644
--- a/embassy-stm32/src/flash/f3.rs
+++ b/embassy-stm32/src/flash/f3.rs
@@ -19,8 +19,10 @@ pub(crate) unsafe fn lock() {
 }
 
 pub(crate) unsafe fn unlock() {
-    pac::FLASH.keyr().write(|w| w.set_fkeyr(0x4567_0123));
-    pac::FLASH.keyr().write(|w| w.set_fkeyr(0xCDEF_89AB));
+    if pac::FLASH.cr().read().lock() {
+        pac::FLASH.keyr().write(|w| w.set_fkeyr(0x4567_0123));
+        pac::FLASH.keyr().write(|w| w.set_fkeyr(0xCDEF_89AB));
+    }
 }
 
 pub(crate) unsafe fn enable_blocking_write() {
diff --git a/embassy-stm32/src/flash/f4.rs b/embassy-stm32/src/flash/f4.rs
index 913950fe..81deaa17 100644
--- a/embassy-stm32/src/flash/f4.rs
+++ b/embassy-stm32/src/flash/f4.rs
@@ -228,8 +228,10 @@ pub(crate) unsafe fn lock() {
 }
 
 pub(crate) unsafe fn unlock() {
-    pac::FLASH.keyr().write(|w| w.set_key(0x45670123));
-    pac::FLASH.keyr().write(|w| w.set_key(0xCDEF89AB));
+    if pac::FLASH.cr().read().lock() {
+        pac::FLASH.keyr().write(|w| w.set_key(0x45670123));
+        pac::FLASH.keyr().write(|w| w.set_key(0xCDEF89AB));
+    }
 }
 
 pub(crate) unsafe fn enable_write() {
diff --git a/embassy-stm32/src/flash/f7.rs b/embassy-stm32/src/flash/f7.rs
index 3a5bdf9c..b52231ca 100644
--- a/embassy-stm32/src/flash/f7.rs
+++ b/embassy-stm32/src/flash/f7.rs
@@ -19,8 +19,10 @@ pub(crate) unsafe fn lock() {
 }
 
 pub(crate) unsafe fn unlock() {
-    pac::FLASH.keyr().write(|w| w.set_key(0x4567_0123));
-    pac::FLASH.keyr().write(|w| w.set_key(0xCDEF_89AB));
+    if pac::FLASH.cr().read().lock() {
+        pac::FLASH.keyr().write(|w| w.set_key(0x4567_0123));
+        pac::FLASH.keyr().write(|w| w.set_key(0xCDEF_89AB));
+    }
 }
 
 pub(crate) unsafe fn enable_blocking_write() {
diff --git a/embassy-stm32/src/flash/g0.rs b/embassy-stm32/src/flash/g0.rs
index 3a457601..19a38897 100644
--- a/embassy-stm32/src/flash/g0.rs
+++ b/embassy-stm32/src/flash/g0.rs
@@ -24,8 +24,10 @@ pub(crate) unsafe fn unlock() {
     while pac::FLASH.sr().read().bsy() {}
 
     // Unlock flash
-    pac::FLASH.keyr().write(|w| w.set_keyr(0x4567_0123));
-    pac::FLASH.keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+    if pac::FLASH.cr().read().lock() {
+        pac::FLASH.keyr().write(|w| w.set_keyr(0x4567_0123));
+        pac::FLASH.keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+    }
 }
 
 pub(crate) unsafe fn enable_blocking_write() {
diff --git a/embassy-stm32/src/flash/h7.rs b/embassy-stm32/src/flash/h7.rs
index 625bf13f..b064fd6e 100644
--- a/embassy-stm32/src/flash/h7.rs
+++ b/embassy-stm32/src/flash/h7.rs
@@ -26,11 +26,15 @@ pub(crate) unsafe fn lock() {
 }
 
 pub(crate) unsafe fn unlock() {
-    pac::FLASH.bank(0).keyr().write(|w| w.set_keyr(0x4567_0123));
-    pac::FLASH.bank(0).keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+    if pac::FLASH.bank(0).cr().read().lock() {
+        pac::FLASH.bank(0).keyr().write(|w| w.set_keyr(0x4567_0123));
+        pac::FLASH.bank(0).keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+    }
     if is_dual_bank() {
-        pac::FLASH.bank(1).keyr().write(|w| w.set_keyr(0x4567_0123));
-        pac::FLASH.bank(1).keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+        if pac::FLASH.bank(1).cr().read().lock() {
+            pac::FLASH.bank(1).keyr().write(|w| w.set_keyr(0x4567_0123));
+            pac::FLASH.bank(1).keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+        }
     }
 }
 
diff --git a/embassy-stm32/src/flash/l.rs b/embassy-stm32/src/flash/l.rs
index 24dcf99b..1db0da92 100644
--- a/embassy-stm32/src/flash/l.rs
+++ b/embassy-stm32/src/flash/l.rs
@@ -28,17 +28,23 @@ pub(crate) unsafe fn lock() {
 pub(crate) unsafe fn unlock() {
     #[cfg(any(flash_wl, flash_wb, flash_l4))]
     {
-        pac::FLASH.keyr().write(|w| w.set_keyr(0x4567_0123));
-        pac::FLASH.keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+        if pac::FLASH.cr().read().lock() {
+            pac::FLASH.keyr().write(|w| w.set_keyr(0x4567_0123));
+            pac::FLASH.keyr().write(|w| w.set_keyr(0xCDEF_89AB));
+        }
     }
 
     #[cfg(any(flash_l0, flash_l1))]
     {
-        pac::FLASH.pekeyr().write(|w| w.set_pekeyr(0x89ABCDEF));
-        pac::FLASH.pekeyr().write(|w| w.set_pekeyr(0x02030405));
+        if pac::FLASH.pecr().read().pelock() {
+            pac::FLASH.pekeyr().write(|w| w.set_pekeyr(0x89ABCDEF));
+            pac::FLASH.pekeyr().write(|w| w.set_pekeyr(0x02030405));
+        }
 
-        pac::FLASH.prgkeyr().write(|w| w.set_prgkeyr(0x8C9DAEBF));
-        pac::FLASH.prgkeyr().write(|w| w.set_prgkeyr(0x13141516));
+        if pac::FLASH.pecr().read().prglock() {
+            pac::FLASH.prgkeyr().write(|w| w.set_prgkeyr(0x8C9DAEBF));
+            pac::FLASH.prgkeyr().write(|w| w.set_prgkeyr(0x13141516));
+        }
     }
 }