diff --git a/os/hal/src/mac.c b/os/hal/src/mac.c
index 553613438..e052e0945 100644
--- a/os/hal/src/mac.c
+++ b/os/hal/src/mac.c
@@ -148,6 +148,7 @@ msg_t macWaitTransmitDescriptor(MACDriver *macp,
                                 MACTransmitDescriptor *tdp,
                                 systime_t time) {
   msg_t msg;
+  systime_t now;
 
   chDbgCheck((macp != NULL) && (tdp != NULL), "macWaitTransmitDescriptor");
   chDbgAssert(macp->state == MAC_ACTIVE, "macWaitTransmitDescriptor(), #1",
@@ -156,7 +157,7 @@ msg_t macWaitTransmitDescriptor(MACDriver *macp,
   while (((msg = mac_lld_get_transmit_descriptor(macp, tdp)) != RDY_OK) &&
          (time > 0)) {
     chSysLock();
-    systime_t now = chTimeNow();
+    now = chTimeNow();
     if ((msg = chSemWaitTimeoutS(&macp->tdsem, time)) == RDY_TIMEOUT) {
       chSysUnlock();
       break;
@@ -206,6 +207,7 @@ msg_t macWaitReceiveDescriptor(MACDriver *macp,
                                MACReceiveDescriptor *rdp,
                                systime_t time) {
   msg_t msg;
+  systime_t now;
 
   chDbgCheck((macp != NULL) && (rdp != NULL), "macWaitReceiveDescriptor");
   chDbgAssert(macp->state == MAC_ACTIVE, "macWaitReceiveDescriptor(), #1",
@@ -214,7 +216,7 @@ msg_t macWaitReceiveDescriptor(MACDriver *macp,
   while (((msg = mac_lld_get_receive_descriptor(macp, rdp)) != RDY_OK) &&
          (time > 0)) {
     chSysLock();
-    systime_t now = chTimeNow();
+    now = chTimeNow();
     if ((msg = chSemWaitTimeoutS(&macp->rdsem, time)) == RDY_TIMEOUT) {
       chSysUnlock();
       break;
diff --git a/readme.txt b/readme.txt
index f1a7289da..d647c8a47 100644
--- a/readme.txt
+++ b/readme.txt
@@ -83,6 +83,8 @@
 *****************************************************************************
 
 *** 2.5.1 ***
+- FIX: Fixed mac.c won't compile due to misplaced declarations (bug 3575657)
+  (backported to 2.4.3).
 - FIX: Fixed STM32F4 ADC prescaler incorrectly initialized (bug 3575297)
   (backported to 2.4.3).
 - FIX: Fixed RCC_APB2ENR_IOPEEN undeclared on STM32F10X_LD_VL devices (bug