diff --git a/chips/atmega1280-hal/avr-atmega1280.json b/chips/atmega1280-hal/avr-atmega1280.json
index 2cd02bbb56..39d031d03f 100644
--- a/chips/atmega1280-hal/avr-atmega1280.json
+++ b/chips/atmega1280-hal/avr-atmega1280.json
@@ -9,6 +9,8 @@
   "target-vendor": "unknown",
   "arch": "avr",
   "data-layout": "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8",
+  "max-atomic-width": 8,
+
   "executables": true,
   "linker": "avr-gcc",
   "linker-flavor": "gcc",
diff --git a/chips/atmega168-hal/avr-atmega168.json b/chips/atmega168-hal/avr-atmega168.json
index 3029bfffb5..076a51e626 100644
--- a/chips/atmega168-hal/avr-atmega168.json
+++ b/chips/atmega168-hal/avr-atmega168.json
@@ -9,6 +9,7 @@
   "target-vendor": "unknown",
   "arch": "avr",
   "data-layout": "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8",
+  "max-atomic-width": 8,
 
   "executables": true,
 
diff --git a/chips/atmega2560-hal/avr-atmega2560.json b/chips/atmega2560-hal/avr-atmega2560.json
index 5839669ed1..a87c94cff4 100644
--- a/chips/atmega2560-hal/avr-atmega2560.json
+++ b/chips/atmega2560-hal/avr-atmega2560.json
@@ -9,6 +9,8 @@
   "target-vendor": "unknown",
   "arch": "avr",
   "data-layout": "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8",
+  "max-atomic-width": 8,
+
   "executables": true,
   "linker": "avr-gcc",
   "linker-flavor": "gcc",
diff --git a/chips/atmega328p-hal/avr-atmega328p.json b/chips/atmega328p-hal/avr-atmega328p.json
index 47d1dce868..0d75250282 100644
--- a/chips/atmega328p-hal/avr-atmega328p.json
+++ b/chips/atmega328p-hal/avr-atmega328p.json
@@ -9,6 +9,7 @@
   "target-vendor": "unknown",
   "arch": "avr",
   "data-layout": "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8",
+  "max-atomic-width": 8,
 
   "executables": true,
 
diff --git a/chips/atmega32u4-hal/avr-atmega32u4.json b/chips/atmega32u4-hal/avr-atmega32u4.json
index 08780d0d33..c2fa755063 100644
--- a/chips/atmega32u4-hal/avr-atmega32u4.json
+++ b/chips/atmega32u4-hal/avr-atmega32u4.json
@@ -9,6 +9,7 @@
   "target-vendor": "unknown",
   "arch": "avr",
   "data-layout": "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8",
+  "max-atomic-width": 8,
 
   "executables": true,
 
diff --git a/chips/atmega48p-hal/avr-atmega48p.json b/chips/atmega48p-hal/avr-atmega48p.json
index 1caf1ea57e..a47a146725 100644
--- a/chips/atmega48p-hal/avr-atmega48p.json
+++ b/chips/atmega48p-hal/avr-atmega48p.json
@@ -9,6 +9,7 @@
   "target-vendor": "unknown",
   "arch": "avr",
   "data-layout": "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8",
+  "max-atomic-width": 8,
 
   "executables": true,
 
diff --git a/chips/attiny85-hal/avr-attiny85.json b/chips/attiny85-hal/avr-attiny85.json
index 292092ab8b..ac8cf5fcbf 100644
--- a/chips/attiny85-hal/avr-attiny85.json
+++ b/chips/attiny85-hal/avr-attiny85.json
@@ -9,6 +9,7 @@
   "target-vendor": "unknown",
   "arch": "avr",
   "data-layout": "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8",
+  "max-atomic-width": 8,
 
   "executables": true,
 
diff --git a/chips/attiny88-hal/avr-attiny88.json b/chips/attiny88-hal/avr-attiny88.json
index 25c666c6c2..fa0222f32d 100644
--- a/chips/attiny88-hal/avr-attiny88.json
+++ b/chips/attiny88-hal/avr-attiny88.json
@@ -9,6 +9,7 @@
   "target-vendor": "unknown",
   "arch": "avr",
   "data-layout": "e-P1-p:16:8-i8:8-i16:8-i32:8-i64:8-f32:8-f64:8-n8-a:8",
+  "max-atomic-width": 8,
 
   "executables": true,