diff --git a/src/device/sam/atsamd51x-bitfields.go b/src/device/sam/atsamd51x-bitfields.go
index adb75ae6..f241f04b 100644
--- a/src/device/sam/atsamd51x-bitfields.go
+++ b/src/device/sam/atsamd51x-bitfields.go
@@ -17,7 +17,8 @@ const (
 	PCHCTRL_GCLK_OSCCTRL_FDPLL1_32K = 3
 	PCHCTRL_GCLK_SDHC0_SLOW         = 3
 	PCHCTRL_GCLK_SDHC1_SLOW         = 3
-	// GCLK_SERCOM[0..7]_SLOW = 3
+	PCHCTRL_GCLK_SERCOMX_SLOW       = 3 // GCLK_SERCOM[0..7]_SLOW = 3
+
 	// FDPLL0 = 3 // 32KHz clock for internal lock timer
 	// FDPLL1 = 3 //32KHz clock for internal lock timer
 	// SDHC0 = 3 // Slow
diff --git a/src/runtime/runtime_atsamd51g19.go b/src/runtime/runtime_atsamd51g19.go
index f422043a..636c6dcd 100644
--- a/src/runtime/runtime_atsamd51g19.go
+++ b/src/runtime/runtime_atsamd51g19.go
@@ -13,7 +13,7 @@ func initSERCOMClocks() {
 		sam.GCLK_PCHCTRL_CHEN)
 
 	// sets the "slow" clock shared by all SERCOM
-	sam.GCLK.PCHCTRL[sam.PCHCTRL_GCLK_SDHC1_SLOW].Set((sam.GCLK_PCHCTRL_GEN_GCLK1 << sam.GCLK_PCHCTRL_GEN_Pos) |
+	sam.GCLK.PCHCTRL[sam.PCHCTRL_GCLK_SERCOMX_SLOW].Set((sam.GCLK_PCHCTRL_GEN_GCLK1 << sam.GCLK_PCHCTRL_GEN_Pos) |
 		sam.GCLK_PCHCTRL_CHEN)
 
 	// Turn on clock to SERCOM1
diff --git a/src/runtime/runtime_atsamd51j19.go b/src/runtime/runtime_atsamd51j19.go
index b3a53236..94e4742e 100644
--- a/src/runtime/runtime_atsamd51j19.go
+++ b/src/runtime/runtime_atsamd51j19.go
@@ -13,7 +13,7 @@ func initSERCOMClocks() {
 		sam.GCLK_PCHCTRL_CHEN)
 
 	// sets the "slow" clock shared by all SERCOM
-	sam.GCLK.PCHCTRL[sam.PCHCTRL_GCLK_SDHC1_SLOW].Set((sam.GCLK_PCHCTRL_GEN_GCLK1 << sam.GCLK_PCHCTRL_GEN_Pos) |
+	sam.GCLK.PCHCTRL[sam.PCHCTRL_GCLK_SERCOMX_SLOW].Set((sam.GCLK_PCHCTRL_GEN_GCLK1 << sam.GCLK_PCHCTRL_GEN_Pos) |
 		sam.GCLK_PCHCTRL_CHEN)
 
 	// Turn on clock to SERCOM1
diff --git a/src/runtime/runtime_atsamd51j20.go b/src/runtime/runtime_atsamd51j20.go
index dd031fa1..a068a08c 100644
--- a/src/runtime/runtime_atsamd51j20.go
+++ b/src/runtime/runtime_atsamd51j20.go
@@ -13,7 +13,7 @@ func initSERCOMClocks() {
 		sam.GCLK_PCHCTRL_CHEN)
 
 	// sets the "slow" clock shared by all SERCOM
-	sam.GCLK.PCHCTRL[sam.PCHCTRL_GCLK_SDHC1_SLOW].Set((sam.GCLK_PCHCTRL_GEN_GCLK1 << sam.GCLK_PCHCTRL_GEN_Pos) |
+	sam.GCLK.PCHCTRL[sam.PCHCTRL_GCLK_SERCOMX_SLOW].Set((sam.GCLK_PCHCTRL_GEN_GCLK1 << sam.GCLK_PCHCTRL_GEN_Pos) |
 		sam.GCLK_PCHCTRL_CHEN)
 
 	// Turn on clock to SERCOM1
diff --git a/src/runtime/runtime_atsamd51p19.go b/src/runtime/runtime_atsamd51p19.go
index 880d0290..43078cb4 100644
--- a/src/runtime/runtime_atsamd51p19.go
+++ b/src/runtime/runtime_atsamd51p19.go
@@ -13,7 +13,7 @@ func initSERCOMClocks() {
 		sam.GCLK_PCHCTRL_CHEN)
 
 	// sets the "slow" clock shared by all SERCOM
-	sam.GCLK.PCHCTRL[sam.PCHCTRL_GCLK_SDHC1_SLOW].Set((sam.GCLK_PCHCTRL_GEN_GCLK1 << sam.GCLK_PCHCTRL_GEN_Pos) |
+	sam.GCLK.PCHCTRL[sam.PCHCTRL_GCLK_SERCOMX_SLOW].Set((sam.GCLK_PCHCTRL_GEN_GCLK1 << sam.GCLK_PCHCTRL_GEN_Pos) |
 		sam.GCLK_PCHCTRL_CHEN)
 
 	// Turn on clock to SERCOM1