diff --git a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA128B1.xml b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA128B1.xml
index 4db3615f..927aa3df 100644
--- a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA128B1.xml
+++ b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA128B1.xml
@@ -621,7 +621,7 @@
                     <bit-field key="frqrange" name="FRQRANGE" description="Frequency Range" mask="0xC0"/>
                     <bit-field key="x32klpm" name="X32KLPM" description="32.768 kHz XTAL OSC Low-power Mode" mask="0x20"/>
                     <bit-field key="xoscpwr" name="XOSCPWR" description="16 MHz Crystal Oscillator High Power mode" mask="0x10"/>
-                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x1F"/>
+                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x0F"/>
                 </register>
                 <register key="xoscfail" name="XOSCFAIL" description="Oscillator Failure Detection Register" offset="0x3" size="1">
                     <bit-field key="pllfdif" name="PLLFDIF" description="PLL Failure Detection Interrupt Flag" mask="0x8"/>
diff --git a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA128B3.xml b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA128B3.xml
index c12854de..5f294157 100644
--- a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA128B3.xml
+++ b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA128B3.xml
@@ -499,7 +499,7 @@
                     <bit-field key="frqrange" name="FRQRANGE" description="Frequency Range" mask="0xC0"/>
                     <bit-field key="x32klpm" name="X32KLPM" description="32.768 kHz XTAL OSC Low-power Mode" mask="0x20"/>
                     <bit-field key="xoscpwr" name="XOSCPWR" description="16 MHz Crystal Oscillator High Power mode" mask="0x10"/>
-                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x1F"/>
+                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x0F"/>
                 </register>
                 <register key="xoscfail" name="XOSCFAIL" description="Oscillator Failure Detection Register" offset="0x3" size="1">
                     <bit-field key="pllfdif" name="PLLFDIF" description="PLL Failure Detection Interrupt Flag" mask="0x8"/>
diff --git a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA16E5.xml b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA16E5.xml
index ad1b7f77..1ff8cd5a 100644
--- a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA16E5.xml
+++ b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA16E5.xml
@@ -508,7 +508,7 @@
                     <bit-field key="frqrange" name="FRQRANGE" description="Frequency Range" mask="0xC0"/>
                     <bit-field key="x32klpm" name="X32KLPM" description="32.768 kHz XTAL OSC Low-power Mode" mask="0x20"/>
                     <bit-field key="xoscpwr" name="XOSCPWR" description="16 MHz Crystal Oscillator High Power mode" mask="0x10"/>
-                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x1F"/>
+                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x0F"/>
                 </register>
                 <register key="xoscfail" name="XOSCFAIL" description="Oscillator Failure Detection Register" offset="0x3" size="1">
                     <bit-field key="pllfdif" name="PLLFDIF" description="PLL Failure Detection Interrupt Flag" mask="0x8"/>
diff --git a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA32E5.xml b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA32E5.xml
index 73bf315d..23c63c88 100644
--- a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA32E5.xml
+++ b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA32E5.xml
@@ -508,7 +508,7 @@
                     <bit-field key="frqrange" name="FRQRANGE" description="Frequency Range" mask="0xC0"/>
                     <bit-field key="x32klpm" name="X32KLPM" description="32.768 kHz XTAL OSC Low-power Mode" mask="0x20"/>
                     <bit-field key="xoscpwr" name="XOSCPWR" description="16 MHz Crystal Oscillator High Power mode" mask="0x10"/>
-                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x1F"/>
+                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x0F"/>
                 </register>
                 <register key="xoscfail" name="XOSCFAIL" description="Oscillator Failure Detection Register" offset="0x3" size="1">
                     <bit-field key="pllfdif" name="PLLFDIF" description="PLL Failure Detection Interrupt Flag" mask="0x8"/>
diff --git a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA64B1.xml b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA64B1.xml
index a5f8625b..8c6ddd56 100644
--- a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA64B1.xml
+++ b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA64B1.xml
@@ -621,7 +621,7 @@
                     <bit-field key="frqrange" name="FRQRANGE" description="Frequency Range" mask="0xC0"/>
                     <bit-field key="x32klpm" name="X32KLPM" description="32.768 kHz XTAL OSC Low-power Mode" mask="0x20"/>
                     <bit-field key="xoscpwr" name="XOSCPWR" description="16 MHz Crystal Oscillator High Power mode" mask="0x10"/>
-                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x1F"/>
+                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x0F"/>
                 </register>
                 <register key="xoscfail" name="XOSCFAIL" description="Oscillator Failure Detection Register" offset="0x3" size="1">
                     <bit-field key="pllfdif" name="PLLFDIF" description="PLL Failure Detection Interrupt Flag" mask="0x8"/>
diff --git a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA64B3.xml b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA64B3.xml
index 6e23be87..2c41a284 100644
--- a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA64B3.xml
+++ b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA64B3.xml
@@ -499,7 +499,7 @@
                     <bit-field key="frqrange" name="FRQRANGE" description="Frequency Range" mask="0xC0"/>
                     <bit-field key="x32klpm" name="X32KLPM" description="32.768 kHz XTAL OSC Low-power Mode" mask="0x20"/>
                     <bit-field key="xoscpwr" name="XOSCPWR" description="16 MHz Crystal Oscillator High Power mode" mask="0x10"/>
-                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x1F"/>
+                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x0F"/>
                 </register>
                 <register key="xoscfail" name="XOSCFAIL" description="Oscillator Failure Detection Register" offset="0x3" size="1">
                     <bit-field key="pllfdif" name="PLLFDIF" description="PLL Failure Detection Interrupt Flag" mask="0x8"/>
diff --git a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA8E5.xml b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA8E5.xml
index cacc2a05..1c277bf7 100644
--- a/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA8E5.xml
+++ b/src/Targets/TargetDescriptionFiles/AVR8/XMEGA/ATXMEGA8E5.xml
@@ -508,7 +508,7 @@
                     <bit-field key="frqrange" name="FRQRANGE" description="Frequency Range" mask="0xC0"/>
                     <bit-field key="x32klpm" name="X32KLPM" description="32.768 kHz XTAL OSC Low-power Mode" mask="0x20"/>
                     <bit-field key="xoscpwr" name="XOSCPWR" description="16 MHz Crystal Oscillator High Power mode" mask="0x10"/>
-                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x1F"/>
+                    <bit-field key="xoscsel" name="XOSCSEL" description="External Oscillator Selection and Startup Time" mask="0x0F"/>
                 </register>
                 <register key="xoscfail" name="XOSCFAIL" description="Oscillator Failure Detection Register" offset="0x3" size="1">
                     <bit-field key="pllfdif" name="PLLFDIF" description="PLL Failure Detection Interrupt Flag" mask="0x8"/>