diff --git a/examples/esp32c3/Cargo.lock b/examples/esp32c3/Cargo.lock
index 6297c40ced..35d467e457 100644
--- a/examples/esp32c3/Cargo.lock
+++ b/examples/esp32c3/Cargo.lock
@@ -17,15 +17,6 @@ version = "1.0.81"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0952808a6c2afd1aa8947271f3a60f1a6763c7b912d210184c5149b5cf147247"
 
-[[package]]
-name = "atomic-polyfill"
-version = "1.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8cf2bce30dfe09ef0bfaef228b9d414faaf7e563035494d7fe092dba54b300f4"
-dependencies = [
- "critical-section",
-]
-
 [[package]]
 name = "autocfg"
 version = "1.1.0"
@@ -611,10 +602,10 @@ dependencies = [
 name = "rtic"
 version = "2.1.1"
 dependencies = [
- "atomic-polyfill",
  "bare-metal",
  "critical-section",
  "esp32c3 0.22.0",
+ "portable-atomic",
  "riscv",
  "rtic-core",
  "rtic-macros",
diff --git a/examples/hifive1/Cargo.lock b/examples/hifive1/Cargo.lock
index 6fcc78644c..76374dcb48 100644
--- a/examples/hifive1/Cargo.lock
+++ b/examples/hifive1/Cargo.lock
@@ -2,15 +2,6 @@
 # It is not intended for manual editing.
 version = 3
 
-[[package]]
-name = "atomic-polyfill"
-version = "1.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8cf2bce30dfe09ef0bfaef228b9d414faaf7e563035494d7fe092dba54b300f4"
-dependencies = [
- "critical-section",
-]
-
 [[package]]
 name = "bare-metal"
 version = "1.0.0"
@@ -268,9 +259,9 @@ dependencies = [
 name = "rtic"
 version = "2.1.1"
 dependencies = [
- "atomic-polyfill",
  "bare-metal",
  "critical-section",
+ "portable-atomic",
  "riscv",
  "riscv-slic",
  "rtic-core",
diff --git a/examples/lm3s6965/Cargo.lock b/examples/lm3s6965/Cargo.lock
index 848a06ff5a..d7537dcafd 100644
--- a/examples/lm3s6965/Cargo.lock
+++ b/examples/lm3s6965/Cargo.lock
@@ -2,15 +2,6 @@
 # It is not intended for manual editing.
 version = 3
 
-[[package]]
-name = "atomic-polyfill"
-version = "1.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8cf2bce30dfe09ef0bfaef228b9d414faaf7e563035494d7fe092dba54b300f4"
-dependencies = [
- "critical-section",
-]
-
 [[package]]
 name = "bare-metal"
 version = "0.2.5"
@@ -309,6 +300,9 @@ name = "portable-atomic"
 version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7170ef9988bc169ba16dd36a7fa041e5c4cbeb6a35b76d4c03daded371eae7c0"
+dependencies = [
+ "critical-section",
+]
 
 [[package]]
 name = "proc-macro-error"
@@ -356,10 +350,10 @@ dependencies = [
 name = "rtic"
 version = "2.1.1"
 dependencies = [
- "atomic-polyfill",
  "bare-metal 1.0.0",
  "cortex-m",
  "critical-section",
+ "portable-atomic",
  "rtic-core",
  "rtic-macros",
 ]
@@ -393,10 +387,10 @@ dependencies = [
 name = "rtic-monotonics"
 version = "2.0.0"
 dependencies = [
- "atomic-polyfill",
  "cfg-if",
  "cortex-m",
  "fugit",
+ "portable-atomic",
  "rtic-time",
 ]
 
diff --git a/examples/lm3s6965/Cargo.toml b/examples/lm3s6965/Cargo.toml
index bfa4b29cbe..5e2cc5034d 100644
--- a/examples/lm3s6965/Cargo.toml
+++ b/examples/lm3s6965/Cargo.toml
@@ -30,7 +30,10 @@ features = ["exit"]
 version = "0.6.0"
 
 [features]
-test-critical-section = ["rtic/test-critical-section"]
+test-critical-section = [
+  "rtic/test-critical-section",
+  "cortex-m/critical-section-single-core",
+]
 thumbv6-backend = ["rtic/thumbv6-backend"]
 thumbv7-backend = ["rtic/thumbv7-backend"]
 thumbv8base-backend = ["rtic/thumbv8base-backend"]
diff --git a/examples/nrf52840_blinky/Cargo.lock b/examples/nrf52840_blinky/Cargo.lock
index ec5f4f9f10..03655d70fa 100644
--- a/examples/nrf52840_blinky/Cargo.lock
+++ b/examples/nrf52840_blinky/Cargo.lock
@@ -2,15 +2,6 @@
 # It is not intended for manual editing.
 version = 3
 
-[[package]]
-name = "atomic-polyfill"
-version = "1.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8cf2bce30dfe09ef0bfaef228b9d414faaf7e563035494d7fe092dba54b300f4"
-dependencies = [
- "critical-section",
-]
-
 [[package]]
 name = "az"
 version = "1.2.1"
@@ -391,9 +382,9 @@ checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
 
 [[package]]
 name = "portable-atomic"
-version = "1.5.1"
+version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3bccab0e7fd7cc19f820a1c8c91720af652d0c88dc9664dd72aef2614f04af3b"
+checksum = "7170ef9988bc169ba16dd36a7fa041e5c4cbeb6a35b76d4c03daded371eae7c0"
 
 [[package]]
 name = "proc-macro-error"
@@ -445,12 +436,12 @@ checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
 
 [[package]]
 name = "rtic"
-version = "2.0.1"
+version = "2.1.1"
 dependencies = [
- "atomic-polyfill",
  "bare-metal 1.0.0",
  "cortex-m",
  "critical-section",
+ "portable-atomic",
  "rtic-core",
  "rtic-macros",
 ]
@@ -471,7 +462,7 @@ checksum = "d9369355b04d06a3780ec0f51ea2d225624db777acbc60abd8ca4832da5c1a42"
 
 [[package]]
 name = "rtic-macros"
-version = "2.0.1"
+version = "2.1.0"
 dependencies = [
  "indexmap",
  "proc-macro-error",
@@ -484,13 +475,12 @@ dependencies = [
 name = "rtic-monotonics"
 version = "2.0.0"
 dependencies = [
- "atomic-polyfill",
  "cfg-if",
  "cortex-m",
  "critical-section",
- "embedded-hal 1.0.0",
  "fugit",
  "nrf52840-pac",
+ "portable-atomic",
  "rtic-time",
 ]
 
diff --git a/examples/rp2040_local_i2c_init/Cargo.lock b/examples/rp2040_local_i2c_init/Cargo.lock
index 66666f85f8..38df88d2de 100644
--- a/examples/rp2040_local_i2c_init/Cargo.lock
+++ b/examples/rp2040_local_i2c_init/Cargo.lock
@@ -8,15 +8,6 @@ version = "0.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "96d30a06541fbafbc7f82ed10c06164cfbd2c401138f6addd8404629c4b16711"
 
-[[package]]
-name = "atomic-polyfill"
-version = "1.0.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c314e70d181aa6053b26e3f7fbf86d1dfff84f816a6175b967666b3506ef7289"
-dependencies = [
- "critical-section",
-]
-
 [[package]]
 name = "bare-metal"
 version = "0.2.5"
@@ -371,6 +362,9 @@ name = "portable-atomic"
 version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7170ef9988bc169ba16dd36a7fa041e5c4cbeb6a35b76d4c03daded371eae7c0"
+dependencies = [
+ "critical-section",
+]
 
 [[package]]
 name = "proc-macro-error"
@@ -503,6 +497,7 @@ dependencies = [
  "embedded-hal 0.2.7",
  "fugit",
  "panic-probe",
+ "portable-atomic",
  "rp-pico",
  "rtic",
  "rtic-monotonics",
@@ -512,10 +507,10 @@ dependencies = [
 name = "rtic"
 version = "2.1.1"
 dependencies = [
- "atomic-polyfill",
  "bare-metal 1.0.0",
  "cortex-m",
  "critical-section",
+ "portable-atomic",
  "rtic-core",
  "rtic-macros",
 ]
@@ -549,10 +544,10 @@ dependencies = [
 name = "rtic-monotonics"
 version = "2.0.0"
 dependencies = [
- "atomic-polyfill",
  "cfg-if",
  "cortex-m",
  "fugit",
+ "portable-atomic",
  "rp2040-pac",
  "rtic-time",
 ]
diff --git a/examples/rp2040_local_i2c_init/Cargo.toml b/examples/rp2040_local_i2c_init/Cargo.toml
index 2f893dc47d..986977d077 100644
--- a/examples/rp2040_local_i2c_init/Cargo.toml
+++ b/examples/rp2040_local_i2c_init/Cargo.toml
@@ -24,6 +24,7 @@ embedded-hal = { version = "0.2.7", features = ["unproven"] }
 fugit = "0.3"
 rp-pico = "0.9.0"
 panic-probe = "0.3"
+portable-atomic = { version = "1", features = ["critical-section"] }
 
 [profile.dev]
 opt-level = 1
diff --git a/examples/stm32f3_blinky/Cargo.lock b/examples/stm32f3_blinky/Cargo.lock
index 527d4eb0ab..d2ed4a8370 100644
--- a/examples/stm32f3_blinky/Cargo.lock
+++ b/examples/stm32f3_blinky/Cargo.lock
@@ -8,15 +8,6 @@ version = "0.1.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e999941b234f3131b00bc13c22d06e8c5ff726d1b6318ac7eb276997bbb4fef0"
 
-[[package]]
-name = "atomic-polyfill"
-version = "1.0.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c314e70d181aa6053b26e3f7fbf86d1dfff84f816a6175b967666b3506ef7289"
-dependencies = [
- "critical-section",
-]
-
 [[package]]
 name = "autocfg"
 version = "1.1.0"
@@ -453,12 +444,12 @@ dependencies = [
 
 [[package]]
 name = "rtic"
-version = "2.0.1"
+version = "2.1.1"
 dependencies = [
- "atomic-polyfill",
  "bare-metal 1.0.0",
  "cortex-m",
  "critical-section",
+ "portable-atomic",
  "rtic-core",
  "rtic-macros",
 ]
@@ -479,7 +470,7 @@ checksum = "d9369355b04d06a3780ec0f51ea2d225624db777acbc60abd8ca4832da5c1a42"
 
 [[package]]
 name = "rtic-macros"
-version = "2.0.1"
+version = "2.1.0"
 dependencies = [
  "indexmap",
  "proc-macro-error",
@@ -492,11 +483,10 @@ dependencies = [
 name = "rtic-monotonics"
 version = "2.0.0"
 dependencies = [
- "atomic-polyfill",
  "cfg-if",
  "cortex-m",
- "embedded-hal 1.0.0",
  "fugit",
+ "portable-atomic",
  "rtic-time",
 ]
 
diff --git a/examples/stm32g030f6_periodic_prints/Cargo.lock b/examples/stm32g030f6_periodic_prints/Cargo.lock
index 65dbf61f02..11bd8c2586 100644
--- a/examples/stm32g030f6_periodic_prints/Cargo.lock
+++ b/examples/stm32g030f6_periodic_prints/Cargo.lock
@@ -2,15 +2,6 @@
 # It is not intended for manual editing.
 version = 3
 
-[[package]]
-name = "atomic-polyfill"
-version = "1.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8cf2bce30dfe09ef0bfaef228b9d414faaf7e563035494d7fe092dba54b300f4"
-dependencies = [
- "critical-section",
-]
-
 [[package]]
 name = "bare-metal"
 version = "0.2.5"
@@ -298,12 +289,12 @@ dependencies = [
 
 [[package]]
 name = "rtic"
-version = "2.0.1"
+version = "2.1.1"
 dependencies = [
- "atomic-polyfill",
  "bare-metal 1.0.0",
  "cortex-m",
  "critical-section",
+ "portable-atomic",
  "rtic-core",
  "rtic-macros",
 ]
@@ -324,7 +315,7 @@ checksum = "d9369355b04d06a3780ec0f51ea2d225624db777acbc60abd8ca4832da5c1a42"
 
 [[package]]
 name = "rtic-macros"
-version = "2.0.1"
+version = "2.1.0"
 dependencies = [
  "indexmap",
  "proc-macro-error",
@@ -337,11 +328,10 @@ dependencies = [
 name = "rtic-monotonics"
 version = "2.0.0"
 dependencies = [
- "atomic-polyfill",
  "cfg-if",
  "cortex-m",
- "embedded-hal 1.0.0",
  "fugit",
+ "portable-atomic",
  "proc-macro2",
  "quote",
  "rtic-time",
@@ -415,6 +405,7 @@ dependencies = [
  "defmt-rtt",
  "fugit",
  "panic-probe",
+ "portable-atomic",
  "rtic",
  "rtic-monotonics",
  "stm32g0xx-hal",
diff --git a/examples/stm32g030f6_periodic_prints/Cargo.toml b/examples/stm32g030f6_periodic_prints/Cargo.toml
index d8d8e352a2..4d79f1f7a9 100644
--- a/examples/stm32g030f6_periodic_prints/Cargo.toml
+++ b/examples/stm32g030f6_periodic_prints/Cargo.toml
@@ -25,6 +25,7 @@ defmt = "0.3.4"
 defmt-rtt = "0.4.0"
 fugit = "0.3.7"
 panic-probe = { version = "0.3.1", features = ["print-defmt"] }
+portable-atomic = { version = "1", features = ["unsafe-assume-single-core"] }
 
 stm32g0xx-hal = { version = "0.2.0", features = ["rt", "stm32g030"] }
 
diff --git a/examples/teensy4_blinky/Cargo.lock b/examples/teensy4_blinky/Cargo.lock
index 8ae5b958c7..d00173af57 100644
--- a/examples/teensy4_blinky/Cargo.lock
+++ b/examples/teensy4_blinky/Cargo.lock
@@ -2,15 +2,6 @@
 # It is not intended for manual editing.
 version = 3
 
-[[package]]
-name = "atomic-polyfill"
-version = "1.0.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8cf2bce30dfe09ef0bfaef228b9d414faaf7e563035494d7fe092dba54b300f4"
-dependencies = [
- "critical-section",
-]
-
 [[package]]
 name = "bare-metal"
 version = "0.2.5"
@@ -109,7 +100,7 @@ dependencies = [
  "proc-macro-error",
  "proc-macro2",
  "quote",
- "syn 2.0.38",
+ "syn 2.0.59",
 ]
 
 [[package]]
@@ -133,17 +124,17 @@ dependencies = [
 
 [[package]]
 name = "embedded-hal"
-version = "1.0.0-rc.3"
+version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bc402f79e1fd22731ca945b4f97b5ff37e7b3f379312595c42bb2e8811c29920"
+checksum = "361a90feb7004eca4019fb28352a9465666b24f840f5c3cddf0ff13920590b89"
 
 [[package]]
 name = "embedded-hal-async"
-version = "1.0.0-rc.3"
+version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fa1fba2ef2ffb35d614acc6fb323ddf7facc45c069f24544d49ea54e5043626d"
+checksum = "0c4c685bbef7fe13c3c6dd4da26841ed3980ef33e841cddfa15ce8a8fb3f1884"
 dependencies = [
- "embedded-hal 1.0.0-rc.3",
+ "embedded-hal 1.0.0",
 ]
 
 [[package]]
@@ -358,9 +349,9 @@ checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
 
 [[package]]
 name = "portable-atomic"
-version = "1.5.1"
+version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3bccab0e7fd7cc19f820a1c8c91720af652d0c88dc9664dd72aef2614f04af3b"
+checksum = "7170ef9988bc169ba16dd36a7fa041e5c4cbeb6a35b76d4c03daded371eae7c0"
 
 [[package]]
 name = "proc-macro-error"
@@ -388,18 +379,18 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.69"
+version = "1.0.80"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "134c189feb4956b20f6f547d2cf727d4c0fe06722b20a0eec87ed445a97f92da"
+checksum = "a56dea16b0a29e94408b9aa5e2940a4eedbd128a1ba20e8f7ae60fd3d465af0e"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.33"
+version = "1.0.36"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5267fca4496028628a95160fc423a33e8b2e6af8a5302579e322e4b520293cae"
+checksum = "0fa76aaf39101c457836aec0ce2316dbdc3ab723cdda1c6bd4e6ad4208acaca7"
 dependencies = [
  "proc-macro2",
 ]
@@ -412,12 +403,12 @@ checksum = "46b71a9d9206e8b46714c74255adcaea8b11e0350c1d8456165073c3f75fc81a"
 
 [[package]]
 name = "rtic"
-version = "2.0.1"
+version = "2.1.1"
 dependencies = [
- "atomic-polyfill",
  "bare-metal 1.0.0",
  "cortex-m",
  "critical-section",
+ "portable-atomic",
  "rtic-core",
  "rtic-macros",
 ]
@@ -438,25 +429,24 @@ checksum = "d9369355b04d06a3780ec0f51ea2d225624db777acbc60abd8ca4832da5c1a42"
 
 [[package]]
 name = "rtic-macros"
-version = "2.0.1"
+version = "2.1.0"
 dependencies = [
  "indexmap",
  "proc-macro-error",
  "proc-macro2",
  "quote",
- "syn 1.0.109",
+ "syn 2.0.59",
 ]
 
 [[package]]
 name = "rtic-monotonics"
 version = "2.0.0"
 dependencies = [
- "atomic-polyfill",
  "cfg-if",
  "cortex-m",
- "embedded-hal 1.0.0-rc.3",
  "fugit",
  "imxrt-ral",
+ "portable-atomic",
  "rtic-time",
 ]
 
@@ -465,7 +455,7 @@ name = "rtic-time"
 version = "2.0.0"
 dependencies = [
  "critical-section",
- "embedded-hal 1.0.0-rc.3",
+ "embedded-hal 1.0.0",
  "embedded-hal-async",
  "fugit",
  "futures-util",
@@ -509,9 +499,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "2.0.38"
+version = "2.0.59"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e96b79aaa137db8f61e26363a0c9b47d8b4ec75da28b7d1d614c2303e232408b"
+checksum = "4a6531ffc7b071655e4ce2e04bd464c4830bb585a61cabb96cf808f05172615a"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -574,7 +564,7 @@ checksum = "266b2e40bc00e5a6c09c3584011e08b06f123c00362c92b975ba9843aaaa14b8"
 dependencies = [
  "proc-macro2",
  "quote",
- "syn 2.0.38",
+ "syn 2.0.59",
 ]
 
 [[package]]
diff --git a/rtic-monotonics/CHANGELOG.md b/rtic-monotonics/CHANGELOG.md
index 1a4211775e..3000f889b0 100644
--- a/rtic-monotonics/CHANGELOG.md
+++ b/rtic-monotonics/CHANGELOG.md
@@ -17,6 +17,7 @@ For each category, *Added*, *Changed*, *Fixed* add new entries at the top!
 
 ### Changed
 
+- Replace `atomic-polyfill` with `portable-atomic`
 - Rework all timers based on `rtic-time 2.0.0`
 - Most timer tick rates are now configurable
 - Tweak `build.rs` to avoid warnings in Nightly 1.78+
diff --git a/rtic-monotonics/Cargo.toml b/rtic-monotonics/Cargo.toml
index 156f9b2f3c..369de915b1 100644
--- a/rtic-monotonics/Cargo.toml
+++ b/rtic-monotonics/Cargo.toml
@@ -36,7 +36,7 @@ rustdoc-flags = ["--cfg", "docsrs"]
 [dependencies]
 rtic-time = { version = "2.0.0", path = "../rtic-time" }
 fugit = { version = "0.3.6" }
-atomic-polyfill = "1"
+portable-atomic = { version = "1" }
 cfg-if = "1.0.0"
 cortex-m = { version = "0.7.6", optional = true }
 critical-section = { version = "1", optional = true }
diff --git a/rtic-monotonics/src/imxrt.rs b/rtic-monotonics/src/imxrt.rs
index bfe63153b0..f413d5c4c2 100644
--- a/rtic-monotonics/src/imxrt.rs
+++ b/rtic-monotonics/src/imxrt.rs
@@ -26,7 +26,7 @@
 //! }
 //! ```
 
-use atomic_polyfill::{AtomicU32, Ordering};
+use portable_atomic::{AtomicU32, Ordering};
 use rtic_time::{
     half_period_counter::calculate_now,
     timer_queue::{TimerQueue, TimerQueueBackend},
diff --git a/rtic-monotonics/src/nrf/rtc.rs b/rtic-monotonics/src/nrf/rtc.rs
index 6437f979a3..f76e319344 100644
--- a/rtic-monotonics/src/nrf/rtc.rs
+++ b/rtic-monotonics/src/nrf/rtc.rs
@@ -61,7 +61,7 @@ pub use nrf5340_net_pac::{self as pac, RTC0_NS as RTC0, RTC1_NS as RTC1};
 #[doc(hidden)]
 pub use nrf9160_pac::{self as pac, RTC0_NS as RTC0, RTC1_NS as RTC1};
 
-use atomic_polyfill::{AtomicU32, Ordering};
+use portable_atomic::{AtomicU32, Ordering};
 use rtic_time::{
     half_period_counter::calculate_now,
     timer_queue::{TimerQueue, TimerQueueBackend},
diff --git a/rtic-monotonics/src/nrf/timer.rs b/rtic-monotonics/src/nrf/timer.rs
index 35e37435f4..6bf1968938 100644
--- a/rtic-monotonics/src/nrf/timer.rs
+++ b/rtic-monotonics/src/nrf/timer.rs
@@ -71,7 +71,7 @@ pub use nrf5340_net_pac::{
 #[doc(hidden)]
 pub use nrf9160_pac::{self as pac, TIMER0_NS as TIMER0, TIMER1_NS as TIMER1, TIMER2_NS as TIMER2};
 
-use atomic_polyfill::{AtomicU32, Ordering};
+use portable_atomic::{AtomicU32, Ordering};
 use rtic_time::{
     half_period_counter::calculate_now,
     timer_queue::{TimerQueue, TimerQueueBackend},
diff --git a/rtic-monotonics/src/stm32.rs b/rtic-monotonics/src/stm32.rs
index 4952882ef1..6b3e4c97f0 100644
--- a/rtic-monotonics/src/stm32.rs
+++ b/rtic-monotonics/src/stm32.rs
@@ -51,7 +51,7 @@ pub mod prelude {
     pub use fugit::{self, ExtU64, ExtU64Ceil};
 }
 
-use atomic_polyfill::{AtomicU64, Ordering};
+use portable_atomic::{AtomicU64, Ordering};
 use rtic_time::{
     half_period_counter::calculate_now,
     timer_queue::{TimerQueue, TimerQueueBackend},
diff --git a/rtic-monotonics/src/systick.rs b/rtic-monotonics/src/systick.rs
index 37cc2edf92..288c7dc4c9 100644
--- a/rtic-monotonics/src/systick.rs
+++ b/rtic-monotonics/src/systick.rs
@@ -42,17 +42,17 @@ pub mod prelude {
 
 pub use cortex_m::peripheral::SYST;
 
-use atomic_polyfill::Ordering;
+use portable_atomic::Ordering;
 use rtic_time::timer_queue::TimerQueue;
 
 use crate::TimerQueueBackend;
 
 cfg_if::cfg_if! {
     if #[cfg(feature = "systick-64bit")] {
-        use atomic_polyfill::AtomicU64;
+        use portable_atomic::AtomicU64;
         static SYSTICK_CNT: AtomicU64 = AtomicU64::new(0);
     } else {
-        use atomic_polyfill::AtomicU32;
+        use portable_atomic::AtomicU32;
         static SYSTICK_CNT: AtomicU32 = AtomicU32::new(0);
     }
 }
diff --git a/rtic/CHANGELOG.md b/rtic/CHANGELOG.md
index fbfe3edca4..ac5436eb73 100644
--- a/rtic/CHANGELOG.md
+++ b/rtic/CHANGELOG.md
@@ -11,6 +11,7 @@ For each category, *Added*, *Changed*, *Fixed* add new entries at the top!
 
 - Updated esp32c3 dependency to v0.22.0
 - Use `riscv-slic` from `crates.io`
+- Replace `atomic-polyfill` with `portable-atomic`
 - Remove unused dependency `rtic-monotonics`
 
 ## [v2.1.1] - 2024-03-13
diff --git a/rtic/Cargo.toml b/rtic/Cargo.toml
index d21246c2f5..7170fc4de3 100644
--- a/rtic/Cargo.toml
+++ b/rtic/Cargo.toml
@@ -30,8 +30,7 @@ esp32c3 = { version = "0.22.0", optional = true }
 riscv = { version = "0.11.0", optional = true }
 cortex-m = { version = "0.7.0", optional = true }
 bare-metal = "1.0.0"
-# portable-atomic = { version = "0.3.19" }
-atomic-polyfill = "1"
+portable-atomic = { version = "1", default-features = false }
 rtic-macros = { path = "../rtic-macros", version = "=2.1.0" }
 rtic-core = "1"
 critical-section = "1"
@@ -68,4 +67,4 @@ riscv-clint-backend = [
 ]
 
 # needed for testing
-test-critical-section = ["cortex-m/critical-section-single-core"]
+test-critical-section = ["portable-atomic/critical-section"]
diff --git a/rtic/src/export.rs b/rtic/src/export.rs
index 4fd8e7870a..aa90ccc6e0 100644
--- a/rtic/src/export.rs
+++ b/rtic/src/export.rs
@@ -1,6 +1,5 @@
 pub use bare_metal::CriticalSection;
-//pub use portable_atomic as atomic;
-pub use atomic_polyfill as atomic;
+pub use portable_atomic as atomic;
 
 pub mod executor;
 
diff --git a/xtask/src/argument_parsing.rs b/xtask/src/argument_parsing.rs
index d7301f4a22..14920fdf72 100644
--- a/xtask/src/argument_parsing.rs
+++ b/xtask/src/argument_parsing.rs
@@ -73,20 +73,20 @@ impl Package {
                     ][..]
                 } else {
                     &[
-                        "cortex-m-systick",
-                        "cortex-m-systick,systick-64bit",
-                        "rp2040",
-                        "nrf52805",
-                        "nrf52810",
-                        "nrf52811",
-                        "nrf52832",
-                        "nrf52833",
-                        "nrf52840",
-                        "nrf5340-app",
-                        "nrf5340-net",
-                        "nrf9160",
-                        "imxrt_gpt1,imxrt_gpt2,imxrt-ral/imxrt1062",
-                        "stm32_tim2,stm32_tim3,stm32_tim4,stm32_tim5,stm32_tim15,stm32h725ag",
+                        "cortex-m-systick,portable-atomic/critical-section",
+                        "cortex-m-systick,systick-64bit,portable-atomic/critical-section",
+                        "rp2040,portable-atomic/critical-section",
+                        "nrf52805,portable-atomic/critical-section",
+                        "nrf52810,portable-atomic/critical-section",
+                        "nrf52811,portable-atomic/critical-section",
+                        "nrf52832,portable-atomic/critical-section",
+                        "nrf52833,portable-atomic/critical-section",
+                        "nrf52840,portable-atomic/critical-section",
+                        "nrf5340-app,portable-atomic/critical-section",
+                        "nrf5340-net,portable-atomic/critical-section",
+                        "nrf9160,portable-atomic/critical-section",
+                        "imxrt_gpt1,imxrt_gpt2,imxrt-ral/imxrt1062,portable-atomic/critical-section",
+                        "stm32_tim2,stm32_tim3,stm32_tim4,stm32_tim5,stm32_tim15,stm32h725ag,portable-atomic/critical-section",
                     ][..]
                 };