diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a6e7a94..e974f8d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,7 +16,7 @@ jobs:
       matrix:
         toolchain:
           # Don't forget to update the README when bumping MSRV.
-          - 1.66.0
+          - 1.81.0
           - stable
           - beta
           - nightly
diff --git a/Cargo.lock b/Cargo.lock
index 91b195b..193bd43 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -11,12 +11,6 @@ dependencies = [
  "memchr",
 ]
 
-[[package]]
-name = "android-tzdata"
-version = "0.1.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e999941b234f3131b00bc13c22d06e8c5ff726d1b6318ac7eb276997bbb4fef0"
-
 [[package]]
 name = "android_system_properties"
 version = "0.1.5"
@@ -32,6 +26,12 @@ version = "0.1.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4b46cbb362ab8752921c97e041f5e366ee6297bd428a31275b9fcf1e380f7299"
 
+[[package]]
+name = "anstyle"
+version = "1.0.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "862ed96ca487e809f1c8e5a8447f6ee2cf102f846893800b20cebdf541fc6bbd"
+
 [[package]]
 name = "autocfg"
 version = "1.5.0"
@@ -53,12 +53,6 @@ version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5e764a1d40d510daf35e07be9eb06e75770908c27d411ee6c92109c9840eaaf7"
 
-[[package]]
-name = "bitflags"
-version = "1.3.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
-
 [[package]]
 name = "bitflags"
 version = "2.9.4"
@@ -87,12 +81,6 @@ dependencies = [
  "shlex",
 ]
 
-[[package]]
-name = "cfg-if"
-version = "0.1.10"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
-
 [[package]]
 name = "cfg-if"
 version = "1.0.3"
@@ -101,16 +89,15 @@ checksum = "2fd1289c04a9ea8cb22300a459a72a385d7c73d3259e2ed7dcb2af674838cfa9"
 
 [[package]]
 name = "chrono"
-version = "0.4.39"
+version = "0.4.42"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e36cc9d416881d2e24f9a963be5fb1cd90966419ac844274161d10488b3e825"
+checksum = "145052bdd345b87320e369255277e3fb5152762ad123a901ef5c262dd38fe8d2"
 dependencies = [
- "android-tzdata",
  "iana-time-zone",
  "js-sys",
  "num-traits",
  "wasm-bindgen",
- "windows-targets",
+ "windows-link 0.2.0",
 ]
 
 [[package]]
@@ -142,28 +129,28 @@ dependencies = [
 
 [[package]]
 name = "clap"
-version = "4.2.0"
+version = "4.5.47"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6efb5f0a41b5ef5b50c5da28c07609c20091df0c1fc33d418fa2a7e693c2b624"
+checksum = "7eac00902d9d136acd712710d71823fb8ac8004ca445a89e73a41d45aa712931"
 dependencies = [
  "clap_builder",
 ]
 
 [[package]]
 name = "clap_builder"
-version = "4.2.0"
+version = "4.5.47"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "671fcaa5debda4b9a84aa7fde49c907c8986c0e6ab927e04217c9cb74e7c8bc9"
+checksum = "2ad9bbf750e73b5884fb8a211a9424a1906c1e156724260fdae972f31d70e1d6"
 dependencies = [
- "bitflags 1.3.2",
+ "anstyle",
  "clap_lex",
 ]
 
 [[package]]
 name = "clap_lex"
-version = "0.4.1"
+version = "0.7.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8a2dd5a6fe8c6e3502f568a6353e5273bbb15193ad9a89e457b9970798efbea1"
+checksum = "b94f61472cee1439c0b966b47e3aca9ae07e45d070759512cd390ea2bebc6675"
 
 [[package]]
 name = "core-foundation-sys"
@@ -173,25 +160,22 @@ checksum = "773648b94d0e5d620f64f280777445740e61fe701025087ec8b57f45c791888b"
 
 [[package]]
 name = "criterion"
-version = "0.5.1"
+version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f2b12d017a929603d80db1831cd3a24082f8137ce19c69e6447f54f5fc8d692f"
+checksum = "e1c047a62b0cc3e145fa84415a3191f628e980b194c2755aa12300a4e6cbd928"
 dependencies = [
  "anes",
  "cast",
  "ciborium",
  "clap",
  "criterion-plot",
- "is-terminal",
  "itertools",
  "num-traits",
- "once_cell",
  "oorandom",
  "plotters",
  "rayon",
  "regex",
  "serde",
- "serde_derive",
  "serde_json",
  "tinytemplate",
  "walkdir",
@@ -199,9 +183,9 @@ dependencies = [
 
 [[package]]
 name = "criterion-plot"
-version = "0.5.0"
+version = "0.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6b50826342786a51a89e2da3a28f1c32b06e387201bc2d19791f622c673706b1"
+checksum = "9b1bcc0dc7dfae599d84ad0b1a55f80cde8af3725da8313b528da95ef783e338"
 dependencies = [
  "cast",
  "itertools",
@@ -209,51 +193,28 @@ dependencies = [
 
 [[package]]
 name = "crossbeam-deque"
-version = "0.7.4"
+version = "0.8.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c20ff29ded3204c5106278a81a38f4b482636ed4fa1e6cfbeef193291beb29ed"
+checksum = "9dd111b7b7f7d55b72c0a6ae361660ee5853c9af73f70c3c2ef6858b950e2e51"
 dependencies = [
  "crossbeam-epoch",
  "crossbeam-utils",
- "maybe-uninit",
 ]
 
 [[package]]
 name = "crossbeam-epoch"
-version = "0.8.2"
+version = "0.9.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "058ed274caafc1f60c4997b5fc07bf7dc7cca454af7c6e81edffe5f33f70dace"
+checksum = "5b82ac4a3c2ca9c3460964f020e1402edd5753411d7737aa39c3714ad1b5420e"
 dependencies = [
- "autocfg",
- "cfg-if 0.1.10",
  "crossbeam-utils",
- "lazy_static",
- "maybe-uninit",
- "memoffset",
- "scopeguard",
-]
-
-[[package]]
-name = "crossbeam-queue"
-version = "0.2.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "774ba60a54c213d409d5353bda12d49cd68d14e45036a285234c8d6f91f92570"
-dependencies = [
- "cfg-if 0.1.10",
- "crossbeam-utils",
- "maybe-uninit",
 ]
 
 [[package]]
 name = "crossbeam-utils"
-version = "0.7.2"
+version = "0.8.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c3c7c73a2d1e9fc0886a08b93e98eb643461230d5f1925e4036204d5f2e261a8"
-dependencies = [
- "autocfg",
- "cfg-if 0.1.10",
- "lazy_static",
-]
+checksum = "d0a5c400df2834b80a4c3327b3aad3a4c4cd4de0629063962b03235697506a28"
 
 [[package]]
 name = "crunchy"
@@ -261,6 +222,18 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "460fbee9c2c2f33933d720630a6a0bac33ba7053db5344fac858d4b8952d77d5"
 
+[[package]]
+name = "derive-ex"
+version = "0.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bba95f299f6b9cd47f68a847eca2ae9060a2713af532dc35c342065544845407"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "structmeta",
+ "syn",
+]
+
 [[package]]
 name = "either"
 version = "1.15.0"
@@ -311,7 +284,7 @@ version = "0.2.16"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "335ff9f135e4384c8150d6f27c6daed433577f86b4750418338c01a1a2528592"
 dependencies = [
- "cfg-if 1.0.3",
+ "cfg-if",
  "libc",
  "wasi 0.11.1+wasi-snapshot-preview1",
 ]
@@ -322,7 +295,7 @@ version = "0.3.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "26145e563e54f2cadc477553f1ec5ee650b00862f0a58bcd12cbdc5f0ea2d2f4"
 dependencies = [
- "cfg-if 1.0.3",
+ "cfg-if",
  "libc",
  "r-efi",
  "wasi 0.14.5+wasi-0.2.4",
@@ -330,19 +303,14 @@ dependencies = [
 
 [[package]]
 name = "half"
-version = "2.2.0"
+version = "2.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6c467d36af040b7b2681f5fddd27427f6da8d3d072f575a265e181d2f8e8d157"
+checksum = "459196ed295495a68f7d7fe1d84f6c4b7ff0e21fe3017b2f283c6fac3ad803c9"
 dependencies = [
+ "cfg-if",
  "crunchy",
 ]
 
-[[package]]
-name = "hermit-abi"
-version = "0.5.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fc0fef456e4baa96da950455cd02c081ca953b141298e41db3fc7e36b1da849c"
-
 [[package]]
 name = "iana-time-zone"
 version = "0.1.63"
@@ -367,22 +335,11 @@ dependencies = [
  "cc",
 ]
 
-[[package]]
-name = "is-terminal"
-version = "0.4.16"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e04d7f318608d35d4b61ddd75cbdaee86b023ebe2bd5a66ee0915f0bf93095a9"
-dependencies = [
- "hermit-abi",
- "libc",
- "windows-sys",
-]
-
 [[package]]
 name = "itertools"
-version = "0.10.5"
+version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b0fd2260e829bddf4cb6ea802289de2f86d6a7a690192fbe91b3f46e0f2c8473"
+checksum = "413ee7dfc52ee1a4949ceeb7dbc8a33f2d6c088194d9f922fb8318faf1f01186"
 dependencies = [
  "either",
 ]
@@ -427,27 +384,12 @@ version = "0.4.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "34080505efa8e45a4b816c349525ebe327ceaa8559756f0356cba97ef3bf7432"
 
-[[package]]
-name = "maybe-uninit"
-version = "2.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "60302e4db3a61da70c0cb7991976248362f30319e88850c487b9b95bbf059e00"
-
 [[package]]
 name = "memchr"
 version = "2.7.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "32a282da65faaf38286cf3be983213fcf1d2e2a58700e808f83f4ea9a4804bc0"
 
-[[package]]
-name = "memoffset"
-version = "0.5.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "043175f069eda7b85febe4a74abbaeff828d9f8b448515d3151a14a3542811aa"
-dependencies = [
- "autocfg",
-]
-
 [[package]]
 name = "num"
 version = "0.2.1"
@@ -524,16 +466,6 @@ dependencies = [
  "autocfg",
 ]
 
-[[package]]
-name = "num_cpus"
-version = "1.17.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "91df4bbde75afed763b708b7eee1e8e7651e02d97f6d5dd763e89367e957b23b"
-dependencies = [
- "hermit-abi",
- "libc",
-]
-
 [[package]]
 name = "once_cell"
 version = "1.21.3"
@@ -609,11 +541,11 @@ checksum = "6fcdab19deb5195a31cf7726a210015ff1496ba1464fd42cb4f537b8b01b471f"
 dependencies = [
  "bit-set",
  "bit-vec",
- "bitflags 2.9.4",
+ "bitflags",
  "lazy_static",
  "num-traits",
  "rand 0.9.2",
- "rand_chacha 0.9.0",
+ "rand_chacha",
  "rand_xorshift",
  "regex-syntax",
  "rusty-fork",
@@ -659,8 +591,6 @@ version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
 dependencies = [
- "libc",
- "rand_chacha 0.3.1",
  "rand_core 0.6.4",
 ]
 
@@ -670,20 +600,10 @@ version = "0.9.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "6db2770f06117d490610c7488547d543617b21bfa07796d7a12f6f1bd53850d1"
 dependencies = [
- "rand_chacha 0.9.0",
+ "rand_chacha",
  "rand_core 0.9.3",
 ]
 
-[[package]]
-name = "rand_chacha"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
-dependencies = [
- "ppv-lite86",
- "rand_core 0.6.4",
-]
-
 [[package]]
 name = "rand_chacha"
 version = "0.9.0"
@@ -730,7 +650,7 @@ dependencies = [
  "permutator",
  "proptest",
  "quickcheck",
- "rand 0.8.5",
+ "rand 0.9.2",
  "rustc_version",
  "serde",
  "serde_json",
@@ -739,26 +659,22 @@ dependencies = [
 
 [[package]]
 name = "rayon"
-version = "1.3.0"
+version = "1.11.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "db6ce3297f9c85e16621bb8cca38a06779ffc31bb8184e1be4bed2be4678a098"
+checksum = "368f01d005bf8fd9b1206fb6fa653e6c4a81ceb1466406b81792d87c5677a58f"
 dependencies = [
- "crossbeam-deque",
  "either",
  "rayon-core",
 ]
 
 [[package]]
 name = "rayon-core"
-version = "1.7.0"
+version = "1.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "08a89b46efaf957e52b18062fb2f4660f8b8a4dde1807ca002690868ef2c85a9"
+checksum = "22e18b0f0062d30d4230b2e85ff77fdfe4326feb054b9783a3460d8435c8ab91"
 dependencies = [
  "crossbeam-deque",
- "crossbeam-queue",
  "crossbeam-utils",
- "lazy_static",
- "num_cpus",
 ]
 
 [[package]]
@@ -805,7 +721,7 @@ version = "1.1.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cd15f8a2c5551a84d56efdc1cd049089e409ac19a3072d5037a17fd70719ff3e"
 dependencies = [
- "bitflags 2.9.4",
+ "bitflags",
  "errno",
  "libc",
  "linux-raw-sys",
@@ -845,12 +761,6 @@ dependencies = [
  "winapi-util",
 ]
 
-[[package]]
-name = "scopeguard"
-version = "1.2.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
-
 [[package]]
 name = "semver"
 version = "1.0.26"
@@ -897,9 +807,9 @@ checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
 
 [[package]]
 name = "structmeta"
-version = "0.2.0"
+version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "78ad9e09554f0456d67a69c1584c9798ba733a5b50349a6c0d0948710523922d"
+checksum = "2e1575d8d40908d70f6fd05537266b90ae71b15dbbe7a8b7dffa2b759306d329"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -909,9 +819,9 @@ dependencies = [
 
 [[package]]
 name = "structmeta-derive"
-version = "0.2.0"
+version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a60bcaff7397072dca0017d1db428e30d5002e00b6847703e2e42005c95fbe00"
+checksum = "152a0b65a590ff6c3da95cabe2353ee04e6167c896b28e3b14478c2636c922fc"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -944,10 +854,11 @@ dependencies = [
 
 [[package]]
 name = "test-strategy"
-version = "0.3.1"
+version = "0.4.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b8361c808554228ad09bfed70f5c823caf8a3450b6881cc3a38eb57e8c08c1d9"
+checksum = "43b12f9683de37f9980e485167ee624bfaa0b6b04da661e98e25ef9c2669bc1b"
 dependencies = [
+ "derive-ex",
  "proc-macro2",
  "quote",
  "structmeta",
@@ -1025,7 +936,7 @@ version = "0.2.101"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7e14915cadd45b529bb8d1f343c4ed0ac1de926144b746e2710f9cd05df6603b"
 dependencies = [
- "cfg-if 1.0.3",
+ "cfg-if",
  "once_cell",
  "rustversion",
  "wasm-bindgen-macro",
@@ -1105,7 +1016,7 @@ checksum = "c0fdd3ddb90610c7638aa2b3a3ab2904fb9e5cdbecc643ddb3647212781c4ae3"
 dependencies = [
  "windows-implement",
  "windows-interface",
- "windows-link",
+ "windows-link 0.1.3",
  "windows-result",
  "windows-strings",
 ]
@@ -1138,13 +1049,19 @@ version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "5e6ad25900d524eaabdbbb96d20b4311e1e7ae1699af4fb28c17ae66c80d798a"
 
+[[package]]
+name = "windows-link"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "45e46c0661abb7180e7b9c281db115305d49ca1709ab8242adf09666d2173c65"
+
 [[package]]
 name = "windows-result"
 version = "0.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "56f42bd332cc6c8eac5af113fc0c1fd6a8fd2aa08a0119358686e5160d0586c6"
 dependencies = [
- "windows-link",
+ "windows-link 0.1.3",
 ]
 
 [[package]]
@@ -1153,82 +1070,18 @@ version = "0.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "56e6c93f3a0c3b36176cb1327a4958a0353d5d166c2a35cb268ace15e91d3b57"
 dependencies = [
- "windows-link",
+ "windows-link 0.1.3",
 ]
 
 [[package]]
 name = "windows-sys"
-version = "0.59.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
-dependencies = [
- "windows-targets",
-]
-
-[[package]]
-name = "windows-targets"
-version = "0.52.6"
+version = "0.61.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
+checksum = "e201184e40b2ede64bc2ea34968b28e33622acdbbf37104f0e4a33f7abe657aa"
 dependencies = [
- "windows_aarch64_gnullvm",
- "windows_aarch64_msvc",
- "windows_i686_gnu",
- "windows_i686_gnullvm",
- "windows_i686_msvc",
- "windows_x86_64_gnu",
- "windows_x86_64_gnullvm",
- "windows_x86_64_msvc",
+ "windows-link 0.2.0",
 ]
 
-[[package]]
-name = "windows_aarch64_gnullvm"
-version = "0.52.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
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 name = "wit-bindgen"
 version = "0.45.1"
diff --git a/Cargo.toml b/Cargo.toml
index 21c3214..8b4117b 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -14,7 +14,7 @@ Map and set data structures whose keys are stored as ranges.
 Contiguous and overlapping ranges that map to the same value are coalesced into a single range.
 """
 categories = ["data-structures"]
-rust-version = "1.66.0"
+rust-version = "1.81.0"
 exclude = [
     ".github/*",
     "bors.toml",
@@ -32,13 +32,13 @@ permutator = "0.4"
 # to update rangemap's MSRV, too, but until I actually publish
 # a policy on that I'm going to avoid doing a big bump right now.
 # (Later problem!)
-criterion = "= 0.5.1"
-rand = "0.8"
+criterion = "0.7"
+rand = "0.9"
 chrono = "0.4"          # For examples
 rustc_version = "0.4"
 serde_json = "1"
-proptest = "1.4.0"
-test-strategy = "0.3.1"
+proptest = "1.4"
+test-strategy = "0.4"
 
 [features]
 serde1 = ["serde"]
diff --git a/README.md b/README.md
index 76a6772..18a43e7 100644
--- a/README.md
+++ b/README.md
@@ -3,7 +3,7 @@
 [![Crate](https://img.shields.io/crates/v/rangemap.svg)](https://crates.io/crates/rangemap)
 [![Docs](https://docs.rs/rangemap/badge.svg)](https://docs.rs/rangemap)
 [![Build status](https://github.com/jeffparsons/rangemap/workflows/CI/badge.svg)](https://github.com/jeffparsons/rangemap/actions)
-[![Rust](https://img.shields.io/badge/rust-1.66.0%2B-blue.svg?maxAge=3600)](https://github.com/jeffparsons/rangemap) <!-- Don't forget to update the GitHub actions config when bumping minimum Rust version. -->
+[![Rust](https://img.shields.io/badge/rust-1.81.0%2B-blue.svg?maxAge=3600)](https://github.com/jeffparsons/rangemap) <!-- Don't forget to update the GitHub actions config when bumping minimum Rust version. -->
 
 [`RangeMap`] and [`RangeInclusiveMap`] are map data structures whose keys
 are stored as ranges. Contiguous and overlapping ranges that map to the same