diff --git a/Cargo.lock b/Cargo.lock
index 177ff6594e244..c309f10997ca4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1259,16 +1259,16 @@ dependencies = [
 
 [[package]]
 name = "fluent-bundle"
-version = "0.15.3"
+version = "0.16.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7fe0a21ee80050c678013f82edf4b705fe2f26f1f9877593d13198612503f493"
+checksum = "01203cb8918f5711e73891b347816d932046f95f54207710bda99beaeb423bf4"
 dependencies = [
  "fluent-langneg",
  "fluent-syntax",
  "intl-memoizer",
  "intl_pluralrules",
- "rustc-hash 1.1.0",
- "self_cell 0.10.3",
+ "rustc-hash 2.1.1",
+ "self_cell",
  "smallvec",
  "unic-langid",
 ]
@@ -1284,11 +1284,12 @@ dependencies = [
 
 [[package]]
 name = "fluent-syntax"
-version = "0.11.1"
+version = "0.12.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2a530c4694a6a8d528794ee9bbd8ba0122e779629ac908d15ad5a7ae7763a33d"
+checksum = "54f0d287c53ffd184d04d8677f590f4ac5379785529e5e08b1c8083acdd5c198"
 dependencies = [
- "thiserror 1.0.69",
+ "memchr",
+ "thiserror 2.0.12",
 ]
 
 [[package]]
@@ -1934,9 +1935,9 @@ dependencies = [
 
 [[package]]
 name = "intl-memoizer"
-version = "0.5.2"
+version = "0.5.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fe22e020fce238ae18a6d5d8c502ee76a52a6e880d99477657e6acc30ec57bda"
+checksum = "310da2e345f5eb861e7a07ee182262e94975051db9e4223e909ba90f392f163f"
 dependencies = [
  "type-map",
  "unic-langid",
@@ -4832,15 +4833,6 @@ version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "94143f37725109f92c262ed2cf5e59bce7498c01bcc1502d7b9afe439a4e9f49"
 
-[[package]]
-name = "self_cell"
-version = "0.10.3"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e14e4d63b804dc0c7ec4a1e52bcb63f02c7ac94476755aa579edac21e01f915d"
-dependencies = [
- "self_cell 1.2.0",
-]
-
 [[package]]
 name = "self_cell"
 version = "1.2.0"
diff --git a/compiler/rustc_error_messages/Cargo.toml b/compiler/rustc_error_messages/Cargo.toml
index 578af7fc51d40..0951859fa531f 100644
--- a/compiler/rustc_error_messages/Cargo.toml
+++ b/compiler/rustc_error_messages/Cargo.toml
@@ -5,8 +5,8 @@ edition = "2024"
 
 [dependencies]
 # tidy-alphabetical-start
-fluent-bundle = "0.15.2"
-fluent-syntax = "0.11"
+fluent-bundle = "0.16"
+fluent-syntax = "0.12"
 icu_list = "1.2"
 icu_locid = "1.2"
 icu_provider_adapters = "1.2"
diff --git a/compiler/rustc_fluent_macro/Cargo.toml b/compiler/rustc_fluent_macro/Cargo.toml
index ce76b2745eaad..d7ef4280aef05 100644
--- a/compiler/rustc_fluent_macro/Cargo.toml
+++ b/compiler/rustc_fluent_macro/Cargo.toml
@@ -9,8 +9,8 @@ proc-macro = true
 [dependencies]
 # tidy-alphabetical-start
 annotate-snippets = "0.11"
-fluent-bundle = "0.15.2"
-fluent-syntax = "0.11"
+fluent-bundle = "0.16"
+fluent-syntax = "0.12"
 proc-macro2 = "1"
 quote = "1"
 syn = { version = "2", features = ["full"] }
diff --git a/src/tools/tidy/Cargo.toml b/src/tools/tidy/Cargo.toml
index dfdbc0878f263..4835c22021042 100644
--- a/src/tools/tidy/Cargo.toml
+++ b/src/tools/tidy/Cargo.toml
@@ -15,7 +15,7 @@ semver = "1.0"
 serde = { version = "1.0.125", features = ["derive"], optional = true }
 termcolor = "1.1.3"
 rustc-hash = "2.0.0"
-fluent-syntax = "0.11.1"
+fluent-syntax = "0.12"
 similar = "2.5.0"
 toml = "0.7.8"