diff --git a/mongoose.c b/mongoose.c
index b62e8101..edd51ca3 100644
--- a/mongoose.c
+++ b/mongoose.c
@@ -12435,11 +12435,9 @@ MG_IRAM static int is_dualbank(void) {
 }
 
 MG_IRAM static void flash_unlock(void) {
-  static bool unlocked = false;
-  if (unlocked == false) {
+  if (MG_REG(MG_FLASH_BASE + MG_FLASH_CR) & MG_BIT(31)) {
     MG_REG(MG_FLASH_BASE + MG_FLASH_KEYR) = 0x45670123;
     MG_REG(MG_FLASH_BASE + MG_FLASH_KEYR) = 0xcdef89ab;
-    unlocked = true;
   }
 }
 
@@ -12686,13 +12684,14 @@ static uint32_t sectors_per_bank(void) {
 }
 
 static void flash_unlock(void) {
-  static bool unlocked = false;
-  if (unlocked == false) {
+  if (MG_REG(FLASH_NSCR) & MG_BIT(0)) {
     MG_REG(FLASH_KEYR) = 0x45670123;
-    MG_REG(FLASH_KEYR) = 0Xcdef89ab;
+    MG_REG(FLASH_KEYR) = 0xcdef89ab;
+  }
+
+  if (MG_REG(FLASH_OPTCR) & MG_BIT(0)) {
     MG_REG(FLASH_OPTKEYR) = 0x08192a3b;
     MG_REG(FLASH_OPTKEYR) = 0x4c5d6e7f;
-    unlocked = true;
   }
 }
 
@@ -12872,17 +12871,17 @@ MG_IRAM static bool is_dualbank(void) {
 }
 
 MG_IRAM static void flash_unlock(void) {
-  static bool unlocked = false;
-  if (unlocked == false) {
-    MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0x45670123;
-    MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0xcdef89ab;
-    if (is_dualbank()) {
-      MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0x45670123;
-      MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0xcdef89ab;
-    }
-    MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x08192a3b;  // opt reg is "shared"
-    MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x4c5d6e7f;  // thus unlock once
-    unlocked = true;
+  if (MG_REG(FLASH_BASE1 + FLASH_CR) & MG_BIT(0)) {
+	  MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0x45670123;
+	  MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0xcdef89ab;
+  }
+  if (is_dualbank() && MG_REG(FLASH_BASE2 + FLASH_CR) & MG_BIT(0)) {
+	  MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0x45670123;
+	  MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0xcdef89ab;
+  }
+  if (MG_REG(FLASH_BASE1 + FLASH_OPTCR) & MG_BIT(0)) {
+	  MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x08192a3b;  // opt reg is "shared"
+	  MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x4c5d6e7f;  // thus unlock once
   }
 }
 
diff --git a/src/ota_stm32f.c b/src/ota_stm32f.c
index 61cbb9ff..a353f70a 100644
--- a/src/ota_stm32f.c
+++ b/src/ota_stm32f.c
@@ -45,11 +45,9 @@ MG_IRAM static int is_dualbank(void) {
 }
 
 MG_IRAM static void flash_unlock(void) {
-  static bool unlocked = false;
-  if (unlocked == false) {
+  if (MG_REG(MG_FLASH_BASE + MG_FLASH_CR) & MG_BIT(31)) {
     MG_REG(MG_FLASH_BASE + MG_FLASH_KEYR) = 0x45670123;
     MG_REG(MG_FLASH_BASE + MG_FLASH_KEYR) = 0xcdef89ab;
-    unlocked = true;
   }
 }
 
diff --git a/src/ota_stm32h5.c b/src/ota_stm32h5.c
index 59835109..0ad3dcab 100644
--- a/src/ota_stm32h5.c
+++ b/src/ota_stm32h5.c
@@ -39,13 +39,14 @@ static uint32_t sectors_per_bank(void) {
 }
 
 static void flash_unlock(void) {
-  static bool unlocked = false;
-  if (unlocked == false) {
+  if (MG_REG(FLASH_NSCR) & MG_BIT(0)) {
     MG_REG(FLASH_KEYR) = 0x45670123;
-    MG_REG(FLASH_KEYR) = 0Xcdef89ab;
+    MG_REG(FLASH_KEYR) = 0xcdef89ab;
+  }
+
+  if (MG_REG(FLASH_OPTCR) & MG_BIT(0)) {
     MG_REG(FLASH_OPTKEYR) = 0x08192a3b;
     MG_REG(FLASH_OPTKEYR) = 0x4c5d6e7f;
-    unlocked = true;
   }
 }
 
diff --git a/src/ota_stm32h7.c b/src/ota_stm32h7.c
index 95fa40cc..026ae6b4 100644
--- a/src/ota_stm32h7.c
+++ b/src/ota_stm32h7.c
@@ -53,17 +53,17 @@ MG_IRAM static bool is_dualbank(void) {
 }
 
 MG_IRAM static void flash_unlock(void) {
-  static bool unlocked = false;
-  if (unlocked == false) {
-    MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0x45670123;
-    MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0xcdef89ab;
-    if (is_dualbank()) {
-      MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0x45670123;
-      MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0xcdef89ab;
-    }
-    MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x08192a3b;  // opt reg is "shared"
-    MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x4c5d6e7f;  // thus unlock once
-    unlocked = true;
+  if (MG_REG(FLASH_BASE1 + FLASH_CR) & MG_BIT(0)) {
+	  MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0x45670123;
+	  MG_REG(FLASH_BASE1 + FLASH_KEYR) = 0xcdef89ab;
+  }
+  if (is_dualbank() && MG_REG(FLASH_BASE2 + FLASH_CR) & MG_BIT(0)) {
+	  MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0x45670123;
+	  MG_REG(FLASH_BASE2 + FLASH_KEYR) = 0xcdef89ab;
+  }
+  if (MG_REG(FLASH_BASE1 + FLASH_OPTCR) & MG_BIT(0)) {
+	  MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x08192a3b;  // opt reg is "shared"
+	  MG_REG(FLASH_BASE1 + FLASH_OPTKEYR) = 0x4c5d6e7f;  // thus unlock once
   }
 }