diff --git a/Cargo.lock b/Cargo.lock
index 8063c98..b600fe6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -260,30 +260,14 @@ dependencies = [
 
 [[package]]
 name = "elasticlunr-rs"
-version = "2.3.14"
+version = "3.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "60eee99ae400fb1c4521ea3bd678994cb66572754d240449368e8ecd40281569"
+checksum = "b94d9c8df0fe6879ca12e7633fdfe467c503722cc981fc463703472d2b876448"
 dependencies = [
- "lazy_static",
  "regex",
  "serde",
  "serde_derive",
  "serde_json",
- "strum",
- "strum_macros",
-]
-
-[[package]]
-name = "env_logger"
-version = "0.7.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "44533bbbb3bb3c1fa17d9f2e4e38bbbaf8396ba82193c4cb1b6445d711445d36"
-dependencies = [
- "atty",
- "humantime 1.3.0",
- "log",
- "regex",
- "termcolor",
 ]
 
 [[package]]
@@ -293,7 +277,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0b2cf0344971ee6c64c31be0d530793fba457d322dfec2810c453d0ef228f9c3"
 dependencies = [
  "atty",
- "humantime 2.1.0",
+ "humantime",
  "log",
  "regex",
  "termcolor",
@@ -559,15 +543,6 @@ dependencies = [
  "http",
 ]
 
-[[package]]
-name = "heck"
-version = "0.3.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6d621efb26863f0e9924c6ac577e8275e5e6b77455db64ffa6c65c904e9e132c"
-dependencies = [
- "unicode-segmentation",
-]
-
 [[package]]
 name = "hermit-abi"
 version = "0.1.19"
@@ -625,15 +600,6 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c4a1e36c821dbe04574f602848a19f742f4fb3c98d40449f11bcad18d6b17421"
 
-[[package]]
-name = "humantime"
-version = "1.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "df004cfca50ef23c36850aaaa59ad52cc70d0e90243c3c7737a4dd32dc7a3c4f"
-dependencies = [
- "quick-error",
-]
-
 [[package]]
 name = "humantime"
 version = "2.1.0"
@@ -810,9 +776,9 @@ checksum = "a3e378b66a060d48947b590737b30a1be76706c8dd7b8ba0f2fe3989c68a853f"
 
 [[package]]
 name = "mdbook"
-version = "0.4.18"
+version = "0.4.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "74612ae81a3e5ee509854049dfa4c7975ae033c06f5fc4735c7dfbe60ee2a39d"
+checksum = "23f3e133c6d515528745ffd3b9f0c7d975ae039f0b6abb099f2168daa2afb4f9"
 dependencies = [
  "ammonia",
  "anyhow",
@@ -820,7 +786,7 @@ dependencies = [
  "clap",
  "clap_complete",
  "elasticlunr-rs",
- "env_logger 0.7.1",
+ "env_logger",
  "futures-util",
  "gitignore",
  "handlebars",
@@ -832,7 +798,6 @@ dependencies = [
  "pulldown-cmark",
  "regex",
  "serde",
- "serde_derive",
  "serde_json",
  "shlex",
  "tempfile",
@@ -847,7 +812,7 @@ name = "mdbook-toc"
 version = "0.9.0"
 dependencies = [
  "clap",
- "env_logger 0.9.0",
+ "env_logger",
  "log",
  "mdbook",
  "pretty_assertions",
@@ -1227,12 +1192,6 @@ dependencies = [
  "unicase",
 ]
 
-[[package]]
-name = "quick-error"
-version = "1.2.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a1d01941d82fa2ab50be1e79e6714289dd7cde78eba4c074bc5a4374f650dfe0"
-
 [[package]]
 name = "quote"
 version = "1.0.18"
@@ -1345,6 +1304,9 @@ name = "serde"
 version = "1.0.137"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "61ea8d54c77f8315140a05f4c7237403bf38b72704d031543aa1d16abbf517d1"
+dependencies = [
+ "serde_derive",
+]
 
 [[package]]
 name = "serde_derive"
@@ -1482,24 +1444,6 @@ version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
 
-[[package]]
-name = "strum"
-version = "0.21.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "aaf86bbcfd1fa9670b7a129f64fc0c9fcbbfe4f1bc4210e9e98fe71ffc12cde2"
-
-[[package]]
-name = "strum_macros"
-version = "0.21.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d06aaeeee809dbc59eb4556183dd927df67db1540de5be8d3ec0b6636358a5ec"
-dependencies = [
- "heck",
- "proc-macro2",
- "quote",
- "syn",
-]
-
 [[package]]
 name = "syn"
 version = "1.0.95"
@@ -1798,12 +1742,6 @@ dependencies = [
  "tinyvec",
 ]
 
-[[package]]
-name = "unicode-segmentation"
-version = "1.9.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e8820f5d777f6224dc4be3632222971ac30164d4a258d595640799554ebfd99"
-
 [[package]]
 name = "unicode-width"
 version = "0.1.9"
diff --git a/Cargo.toml b/Cargo.toml
index e86fbee..6128fef 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,7 +10,7 @@ edition = "2018"
 rust-version = "1.58"
 
 [dependencies]
-mdbook = "0.4.10"
+mdbook = "0.4.21"
 pulldown-cmark = "0.9.1"
 log = "0.4.11"
 clap = "3.1.18"