diff --git a/os/hal/include/i2c.h b/os/hal/include/i2c.h
index 8b4d692fe..645729cc2 100644
--- a/os/hal/include/i2c.h
+++ b/os/hal/include/i2c.h
@@ -102,7 +102,7 @@ typedef enum {
  */
 #define i2cMasterTransmit(i2cp, addr, txbuf, txbytes, rxbuf, rxbytes)       \
   (i2cMasterTransmitTimeout(i2cp, addr, txbuf, txbytes, rxbuf, rxbytes,     \
-                           TIME_INFINITE))
+                            TIME_INFINITE))
 
 /**
  * @brief   Wrap i2cMasterReceiveTimeout function with TIME_INFINITE timeout.
diff --git a/os/hal/platforms/STM32/i2c_lld.c b/os/hal/platforms/STM32/i2c_lld.c
index 7458d9252..229520a91 100644
--- a/os/hal/platforms/STM32/i2c_lld.c
+++ b/os/hal/platforms/STM32/i2c_lld.c
@@ -165,13 +165,15 @@ static void i2c_lld_abort_operation(I2CDriver *i2cp) {
 static void i2c_lld_safety_timeout(void *p) {
   I2CDriver *i2cp = (I2CDriver *)p;
 
+  chSysLockFromIsr();
   if (i2cp->thread) {
+    Thread *tp = i2cp->thread;
     i2c_lld_abort_operation(i2cp);
-    chSysLockFromIsr();
-    i2cp->thread->p_u.rdymsg = RDY_TIMEOUT;
-    chSchReadyI(i2cp->thread);
-    chSysUnlockFromIsr();
+    i2cp->thread = NULL;
+    tp->p_u.rdymsg = RDY_TIMEOUT;
+    chSchReadyI(tp);
   }
+  chSysUnlockFromIsr();
 }
 
 /**
@@ -768,12 +770,12 @@ msg_t i2c_lld_master_receive_timeout(I2CDriver *i2cp, i2caddr_t addr,
                                      systime_t timeout) {
   I2C_TypeDef *dp = i2cp->i2c;
   VirtualTimer vt;
-  msg_t rdymsg;
 
   chDbgCheck((rxbytes > 1), "i2c_lld_master_receive_timeout");
 
   /* Global timeout for the whole operation.*/
-  chVTSetI(&vt, timeout, i2c_lld_safety_timeout, (void *)i2cp);
+  if (timeout != TIME_INFINITE)
+    chVTSetI(&vt, timeout, i2c_lld_safety_timeout, (void *)i2cp);
 
   /* Releases the lock from high level driver.*/
   chSysUnlock();
@@ -789,10 +791,10 @@ msg_t i2c_lld_master_receive_timeout(I2CDriver *i2cp, i2caddr_t addr,
   /* Waits until BUSY flag is reset and the STOP from the previous operation
      is completed, alternatively for a timeout condition.*/
   while ((dp->SR2 & I2C_SR2_BUSY) || (dp->CR1 & I2C_CR1_STOP)) {
-    if (!chVTIsArmedI(&vt)) {
-      chSysLock();
+    chSysLock();
+    if (!chVTIsArmedI(&vt))
       return RDY_TIMEOUT;
-    }
+    chSysUnlock();
   }
 
   /* This lock will be released in high level driver.*/
@@ -810,11 +812,10 @@ msg_t i2c_lld_master_receive_timeout(I2CDriver *i2cp, i2caddr_t addr,
   /* Waits for the operation completion or a timeout.*/
   i2cp->thread = chThdSelf();
   chSchGoSleepS(THD_STATE_SUSPENDED);
-  rdymsg = chThdSelf()->p_u.rdymsg;
-  if (rdymsg != RDY_TIMEOUT)
+  if (chVTIsArmedI(&vt))
     chVTResetI(&vt);
 
-  return rdymsg;
+  return chThdSelf()->p_u.rdymsg;
 }
 
 /**
@@ -848,13 +849,13 @@ msg_t i2c_lld_master_transmit_timeout(I2CDriver *i2cp, i2caddr_t addr,
                                       systime_t timeout) {
   I2C_TypeDef *dp = i2cp->i2c;
   VirtualTimer vt;
-  msg_t rdymsg;
 
   chDbgCheck(((rxbytes == 0) || ((rxbytes > 1) && (rxbuf != NULL))),
              "i2c_lld_master_transmit_timeout");
 
   /* Global timeout for the whole operation.*/
-  chVTSetI(&vt, timeout, i2c_lld_safety_timeout, (void *)i2cp);
+  if (timeout != TIME_INFINITE)
+    chVTSetI(&vt, timeout, i2c_lld_safety_timeout, (void *)i2cp);
 
   /* Releases the lock from high level driver.*/
   chSysUnlock();
@@ -874,10 +875,10 @@ msg_t i2c_lld_master_transmit_timeout(I2CDriver *i2cp, i2caddr_t addr,
   /* Waits until BUSY flag is reset and the STOP from the previous operation
      is completed, alternatively for a timeout condition.*/
   while ((dp->SR2 & I2C_SR2_BUSY) || (dp->CR1 & I2C_CR1_STOP)) {
-    if (!chVTIsArmedI(&vt)) {
-      chSysLock();
+    chSysLock();
+    if (!chVTIsArmedI(&vt))
       return RDY_TIMEOUT;
-    }
+    chSysUnlock();
   }
 
   /* This lock will be released in high level driver.*/
@@ -895,11 +896,10 @@ msg_t i2c_lld_master_transmit_timeout(I2CDriver *i2cp, i2caddr_t addr,
   /* Waits for the operation completion or a timeout.*/
   i2cp->thread = chThdSelf();
   chSchGoSleepS(THD_STATE_SUSPENDED);
-  rdymsg = chThdSelf()->p_u.rdymsg;
-  if (rdymsg != RDY_TIMEOUT)
+  if (chVTIsArmedI(&vt))
     chVTResetI(&vt);
 
-  return rdymsg;
+  return chThdSelf()->p_u.rdymsg;
 }
 
 #endif /* HAL_USE_I2C */
diff --git a/readme.txt b/readme.txt
index 75cc23fe0..c20f296f5 100644
--- a/readme.txt
+++ b/readme.txt
@@ -81,6 +81,8 @@
 *****************************************************************************
 
 *** 2.5.0 ***
+- FIX: Fixed timeout related race condition in STM32 I2C driver (bug 3530043)
+  (backported to 2.4.2).
 - FIX: Fixed wrong macro check in STM32 MAC driver (bug 3527179)(backported
   to 2.4.2).
 - FIX: Fixed error in STM32L-Discovery board.h file (bug 3526918)(backported