diff --git a/Cargo.lock b/Cargo.lock
index 79fcca75..f5be18d5 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1902,7 +1902,7 @@ dependencies = [
  "crossbeam-channel",
  "csv",
  "delegate 0.13.0",
- "derive_more 0.99.18",
+ "derive_more 1.0.0",
  "downcast-rs",
  "fxhash",
  "hugr",
@@ -1958,7 +1958,7 @@ name = "tket2-py"
 version = "0.0.0"
 dependencies = [
  "cool_asserts",
- "derive_more 0.99.18",
+ "derive_more 1.0.0",
  "hugr",
  "itertools 0.13.0",
  "num_cpus",
diff --git a/Cargo.toml b/Cargo.toml
index 7da38922..20f5a95c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -43,7 +43,7 @@ criterion = "0.5.1"
 crossbeam-channel = "0.5.8"
 csv = "1.2.2"
 delegate = "0.13.0"
-derive_more = "0.99.18"
+derive_more = "1.0.0"
 downcast-rs = "1.2.0"
 fxhash = "0.2.1"
 lazy_static = "1.5.0"