diff --git a/.tool-versions b/.tool-versions
index 2f5b1b0..01f3cd5 100644
--- a/.tool-versions
+++ b/.tool-versions
@@ -1,3 +1,3 @@
-gleam 0.29.0
+gleam 0.30.2
 erlang 25.2.2
 nodejs 18.14.0
diff --git a/CHANGELOG.txt b/CHANGELOG.txt
index 6c6c6c9..0dcefc9 100644
--- a/CHANGELOG.txt
+++ b/CHANGELOG.txt
@@ -1,3 +1,8 @@
+5.0.0
+-----
+
+* Update for Gleam 0.30.
+
 4.0.1
 -----
 
diff --git a/gleam.toml b/gleam.toml
index 18add32..0d7fe65 100644
--- a/gleam.toml
+++ b/gleam.toml
@@ -1,5 +1,5 @@
 name = "glentities"
-version = "4.0.1"
+version = "5.0.0"
 description = "HTML entity encoder/decoder for Gleam"
 
 # Fill out these fields if you intend to generate HTML documentation or publish
@@ -12,7 +12,7 @@ links = []
 internal_modules = ["glentities/internal/*"]
 
 [dependencies]
-gleam_stdlib = "~> 0.29.0"
+gleam_stdlib = "~> 0.29"
 
 [dev-dependencies]
 gleeunit = "~> 0.10"
diff --git a/manifest.toml b/manifest.toml
index 62c5ca0..262a3e6 100644
--- a/manifest.toml
+++ b/manifest.toml
@@ -2,10 +2,10 @@
 # You typically do not need to edit this file
 
 packages = [
-  { name = "gleam_stdlib", version = "0.29.1", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "24581B17879AA903B3E7531869D9460730C2F772A1C02C774ABF75710CCC4CFE" },
+  { name = "gleam_stdlib", version = "0.30.0", build_tools = ["gleam"], requirements = [], otp_app = "gleam_stdlib", source = "hex", outer_checksum = "03710B3DA047A3683117591707FCA19D32B980229DD8CE8B0603EB5B5144F6C3" },
   { name = "gleeunit", version = "0.10.1", build_tools = ["gleam"], requirements = ["gleam_stdlib"], otp_app = "gleeunit", source = "hex", outer_checksum = "ECEA2DE4BE6528D36AFE74F42A21CDF99966EC36D7F25DEB34D47DD0F7977BAF" },
 ]
 
 [requirements]
-gleam_stdlib = "~> 0.29.0"
-gleeunit = "~> 0.10"
+gleam_stdlib = { version = "~> 0.29" }
+gleeunit = { version = "~> 0.10" }
diff --git a/src/ffi_js.mjs b/src/ffi_js.mjs
new file mode 100644
index 0000000..c51089c
--- /dev/null
+++ b/src/ffi_js.mjs
@@ -0,0 +1,3 @@
+export function normalize(str, mode) {
+  return str.normalize(mode);
+}
diff --git a/src/glentities/internal/string_utils.gleam b/src/glentities/internal/string_utils.gleam
index 0657c0a..8d4c54c 100644
--- a/src/glentities/internal/string_utils.gleam
+++ b/src/glentities/internal/string_utils.gleam
@@ -1,13 +1,12 @@
-if erlang {
-  pub external fn normalise(text: String) -> String =
-    "unicode" "characters_to_nfc_binary"
+@target(erlang)
+@external(erlang, "unicode", "characters_to_nfc_binary")
+pub fn normalise(text text: String) -> String
+
+@target(javascript)
+pub fn normalise(text: String) -> String {
+  normalise_js(text, "NFC")
 }
 
-if javascript {
-  pub fn normalise(text: String) -> String {
-    normalise_js(text, "NFC")
-  }
-
-  pub external fn normalise_js(text: String, mode: String) -> String =
-    "" "String.prototype.normalize.call"
-}
+@target(javascript)
+@external(javascript, "../../ffi_js.mjs", "normalize")
+pub fn normalise_js(text text: String, mode mode: String) -> String