diff --git a/tcl/target/stm32f2x.cfg b/tcl/target/stm32f2x.cfg
index 0095615d0..0e734debb 100644
--- a/tcl/target/stm32f2x.cfg
+++ b/tcl/target/stm32f2x.cfg
@@ -84,8 +84,8 @@ $_TARGETNAME configure -event examine-end {
 	mmw 0xE0042004 0x00000007 0
 
 	# Stop watchdog counters during halt
-	# DBGMCU_APB1_FZ = DBG_IWDG_STOP | DBG_WWDG_STOP
-	mww 0xE0042008 0x00001800
+	# DBGMCU_APB1_FZ |= DBG_IWDG_STOP | DBG_WWDG_STOP
+	mmw 0xE0042008 0x00001800 0
 }
 
 $_TARGETNAME configure -event trace-config {
diff --git a/tcl/target/stm32f3x.cfg b/tcl/target/stm32f3x.cfg
index ca8e6e1d8..f3ea40bad 100644
--- a/tcl/target/stm32f3x.cfg
+++ b/tcl/target/stm32f3x.cfg
@@ -99,7 +99,7 @@ proc stm32f3x_default_examine_end {} {
 	mmw 0xe0042004 0x00000007 0 ;# DBGMCU_CR |= DBG_STANDBY | DBG_STOP | DBG_SLEEP
 
 	# Stop watchdog counters during halt
-	mww 0xe0042008 0x00001800 ;# DBGMCU_APB1_FZ = DBG_IWDG_STOP | DBG_WWDG_STOP
+	mmw 0xe0042008 0x00001800 0 ;# DBGMCU_APB1_FZ |= DBG_IWDG_STOP | DBG_WWDG_STOP
 }
 
 proc stm32f3x_default_reset_init {} {
diff --git a/tcl/target/stm32f4x.cfg b/tcl/target/stm32f4x.cfg
index 51d76e7e5..9aadf627a 100644
--- a/tcl/target/stm32f4x.cfg
+++ b/tcl/target/stm32f4x.cfg
@@ -96,8 +96,8 @@ $_TARGETNAME configure -event examine-end {
 	mmw 0xE0042004 0x00000007 0
 
 	# Stop watchdog counters during halt
-	# DBGMCU_APB1_FZ = DBG_IWDG_STOP | DBG_WWDG_STOP
-	mww 0xE0042008 0x00001800
+	# DBGMCU_APB1_FZ |= DBG_IWDG_STOP | DBG_WWDG_STOP
+	mmw 0xE0042008 0x00001800 0
 }
 
 $_TARGETNAME configure -event trace-config {
diff --git a/tcl/target/stm32f7x.cfg b/tcl/target/stm32f7x.cfg
index 833ef9482..166246701 100755
--- a/tcl/target/stm32f7x.cfg
+++ b/tcl/target/stm32f7x.cfg
@@ -80,8 +80,8 @@ $_TARGETNAME configure -event examine-end {
 	mmw 0xE0042004 0x00000007 0
 
 	# Stop watchdog counters during halt
-	# DBGMCU_APB1_FZ = DBG_IWDG_STOP | DBG_WWDG_STOP
-	mww 0xE0042008 0x00001800
+	# DBGMCU_APB1_FZ |= DBG_IWDG_STOP | DBG_WWDG_STOP
+	mmw 0xE0042008 0x00001800 0
 }
 
 $_TARGETNAME configure -event trace-config {
diff --git a/tcl/target/stm32l1.cfg b/tcl/target/stm32l1.cfg
index 7754c8493..790c495b3 100644
--- a/tcl/target/stm32l1.cfg
+++ b/tcl/target/stm32l1.cfg
@@ -114,8 +114,8 @@ $_TARGETNAME configure -event examine-end {
 	mmw 0xE0042004 0x00000007 0
 
 	# Stop watchdog counters during halt
-	# DBGMCU_APB1_FZ = DBG_IWDG_STOP | DBG_WWDG_STOP
-	mww 0xE0042008 0x00001800
+	# DBGMCU_APB1_FZ |= DBG_IWDG_STOP | DBG_WWDG_STOP
+	mmw 0xE0042008 0x00001800 0
 }
 
 $_TARGETNAME configure -event trace-config {