diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index b9c6e50f..8dbdb67d 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -165,7 +165,7 @@ jobs:
         run: |
           cargo check --target=${{ matrix.target }}
           cargo check --target=${{ matrix.target }} --features="portable-atomic-critical-section"
-          cargo check --target=${{ matrix.target }} --features="ufmt serde defmt-03 mpmc_large"
+          cargo check --target=${{ matrix.target }} --features="ufmt serde defmt-1 mpmc_large"
 
   doc:
     name: doc
@@ -208,7 +208,7 @@ jobs:
 
       - name: cargo rustdoc
         env: {"RUSTDOCFLAGS": "-D warnings --cfg docsrs"}
-        run: cargo rustdoc --target=${{ matrix.target }} --features="ufmt serde defmt-03 mpmc_large portable-atomic-critical-section"
+        run: cargo rustdoc --target=${{ matrix.target }} --features="ufmt serde defmt-1 mpmc_large portable-atomic-critical-section"
 
   # Run cpass tests
   testcpass:
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6de5dab8..e062c93d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -44,6 +44,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Changed
 
+- Updated defmt from 0.3 to 1.0.1
+  - Changed the feature name from `defmt-03` to `defmt-1`. 
 - Changed the error type of these methods from `()` to `CapacityError`.
   - `String::push_str`
   - `String::push`
diff --git a/Cargo.toml b/Cargo.toml
index 05e42505..aacddee9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -33,8 +33,8 @@ serde = ["dep:serde"]
 # implement ufmt traits.
 ufmt = ["dep:ufmt-write"]
 
-# Implement defmt::Format from defmt v0.3
-defmt-03 = ["dep:defmt"]
+# Implement defmt::Format from defmt v1
+defmt-1 = ["dep:defmt"]
 
 # Enable larger MPMC sizes.
 mpmc_large = []
@@ -46,7 +46,7 @@ portable-atomic = { version = "1.0", optional = true }
 hash32 = "0.3.0"
 serde = { version = "1", optional = true, default-features = false }
 ufmt-write = { version = "0.1", optional = true }
-defmt = { version = ">=0.2.0,<0.4", optional = true }
+defmt = { version = "1.0.1", optional = true }
 
 # for the pool module
 [target.'cfg(any(target_arch = "arm", target_pointer_width = "32", target_pointer_width = "64"))'.dependencies]
@@ -57,7 +57,7 @@ ufmt = "0.2"
 static_assertions = "1.1.0"
 
 [package.metadata.docs.rs]
-features = ["ufmt", "serde", "defmt-03", "mpmc_large", "portable-atomic-critical-section"]
+features = ["ufmt", "serde", "defmt-1", "mpmc_large", "portable-atomic-critical-section"]
 # for the pool module
 targets = ["i686-unknown-linux-gnu"]
 rustdoc-args = ["--cfg", "docsrs"]
diff --git a/src/lib.rs b/src/lib.rs
index b5fe9a71..8b24ba88 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -192,7 +192,7 @@ mod de;
 mod ser;
 
 pub mod binary_heap;
-#[cfg(feature = "defmt-03")]
+#[cfg(feature = "defmt-1")]
 mod defmt;
 #[cfg(any(
     // assume we have all atomics available if we're using portable-atomic