diff --git a/Cargo.lock b/Cargo.lock
index 474c7bdb08..971dc46228 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -287,7 +287,7 @@ version = "3.1.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "25320346e922cffe59c0bbc5410c8d8784509efb321488971081313cb1e1a33c"
 dependencies = [
- "heck 0.4.0",
+ "heck",
  "proc-macro-error",
  "proc-macro2",
  "quote",
@@ -845,15 +845,6 @@ version = "0.11.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ab5ef0d4909ef3724cc8cce6ccc8572c5c817592e9285f5464f8e86f8bd3726e"
 
-[[package]]
-name = "heck"
-version = "0.3.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6d621efb26863f0e9924c6ac577e8275e5e6b77455db64ffa6c65c904e9e132c"
-dependencies = [
- "unicode-segmentation",
-]
-
 [[package]]
 name = "heck"
 version = "0.4.0"
@@ -1759,7 +1750,7 @@ dependencies = [
  "difference",
  "env_logger 0.9.0",
  "futures 0.3.18",
- "heck 0.3.3",
+ "heck",
  "home",
  "itertools",
  "jsonrpc-core",
diff --git a/Cargo.toml b/Cargo.toml
index e8aa9be54c..83c013f5eb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -59,7 +59,7 @@ ordslice = "0.3"
 crossbeam-channel = "0.5"
 toml = "0.5"
 toml_edit = { version = "0.14.3", features = ["easy"] }
-heck = "0.3"
+heck = "0.4"
 
 # A noop dependency that changes in the Rust repository, it's a bit of a hack.
 # See the `src/tools/rustc-workspace-hack/README.md` file in `rust-lang/rust`
diff --git a/rls/src/config.rs b/rls/src/config.rs
index 195f0e4381..9dd310a4ee 100644
--- a/rls/src/config.rs
+++ b/rls/src/config.rs
@@ -243,7 +243,7 @@ impl Config {
 
         if let serde_json::Value::Object(map) = val {
             let seq = serde::de::value::MapDeserializer::new(map.iter().filter_map(|(k, v)| {
-                use heck::SnakeCase;
+                use heck::ToSnakeCase;
                 let snake_case = k.to_snake_case();
                 let vec = dups.entry(snake_case.clone()).or_default();
                 vec.push(k.to_string());
diff --git a/tests/client.rs b/tests/client.rs
index 48057e1f32..5ae4beac05 100644
--- a/tests/client.rs
+++ b/tests/client.rs
@@ -2193,22 +2193,22 @@ fn client_init_impl(convert_case: fn(&str) -> String) {
 
 #[test]
 fn client_init_with_configuration_mixed_case() {
-    client_init_impl(heck::MixedCase::to_mixed_case);
+    client_init_impl(heck::ToLowerCamelCase::to_lower_camel_case);
 }
 
 #[test]
 fn client_init_with_configuration_camel_case() {
-    client_init_impl(heck::CamelCase::to_camel_case);
+    client_init_impl(heck::ToUpperCamelCase::to_upper_camel_case);
 }
 
 #[test]
 fn client_init_with_configuration_snake_case() {
-    client_init_impl(heck::SnakeCase::to_snake_case);
+    client_init_impl(heck::ToSnakeCase::to_snake_case);
 }
 
 #[test]
 fn client_init_with_configuration_kebab_case() {
-    client_init_impl(heck::KebabCase::to_kebab_case);
+    client_init_impl(heck::ToKebabCase::to_kebab_case);
 }
 
 #[test]