diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6d14d0ac..89d39bdc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Changelog
 
+# 8.12.6
+
+- Require `analyzer 13.0.0`.
+
 # 8.12.5
 
 - Allow `analyzer 11.0.0` and `analyzer 12.0.0`.
diff --git a/benchmark/pubspec.yaml b/benchmark/pubspec.yaml
index 6b8a99d2..867038bb 100644
--- a/benchmark/pubspec.yaml
+++ b/benchmark/pubspec.yaml
@@ -1,5 +1,5 @@
 name: benchmark
-version: 8.12.5
+version: 8.12.6
 publish_to: none
 description: >
   Benchmark, not for publishing.
@@ -14,7 +14,7 @@ dependencies:
 
 dev_dependencies:
   build_runner: '>=1.0.0 <3.0.0'
-  built_value_generator: ^8.12.5
+  built_value_generator: ^8.12.6
   pedantic: ^1.4.0
   quiver: '>=0.21.0 <4.0.0'
   test: ^1.0.0
diff --git a/built_value/pubspec.yaml b/built_value/pubspec.yaml
index 314ef52e..23c6d2d3 100644
--- a/built_value/pubspec.yaml
+++ b/built_value/pubspec.yaml
@@ -1,5 +1,5 @@
 name: built_value
-version: 8.12.5
+version: 8.12.6
 description: >
   Value types with builders, Dart classes as enums, and serialization.
   This library is the runtime dependency.
diff --git a/built_value_generator/lib/src/value_source_class.dart b/built_value_generator/lib/src/value_source_class.dart
index 8f6fba6e..bc187535 100644
--- a/built_value_generator/lib/src/value_source_class.dart
+++ b/built_value_generator/lib/src/value_source_class.dart
@@ -593,13 +593,13 @@ abstract class ValueSourceClass
               .getFragmentDeclaration(
                 method.formalParameters[0].firstFragment,
               )!
-              .node is SimpleFormalParameter &&
+              .node is RegularFormalParameter &&
           DartTypes.stripGenerics(
                 (parsedLibrary
                         .getFragmentDeclaration(
                           method.formalParameters[0].firstFragment,
                         )!
-                        .node as SimpleFormalParameter)
+                        .node as RegularFormalParameter)
                     .type!
                     .toSource(),
               ) ==
diff --git a/built_value_generator/pubspec.yaml b/built_value_generator/pubspec.yaml
index d4dcae6c..a3e317a0 100644
--- a/built_value_generator/pubspec.yaml
+++ b/built_value_generator/pubspec.yaml
@@ -1,5 +1,5 @@
 name: built_value_generator
-version: 8.12.5
+version: 8.12.6
 description: >
   Value types with builders, Dart classes as enums, and serialization.
   This library is the dev dependency.
@@ -13,7 +13,7 @@ environment:
   sdk: '>=3.6.0 <4.0.0'
 
 dependencies:
-  analyzer: '>=10.0.0 <13.0.0'
+  analyzer: ^13.0.0
   build: '>=3.0.0 <5.0.0'
   build_config: ^1.2.0
   built_collection: ^5.0.0
diff --git a/built_value_test/pubspec.yaml b/built_value_test/pubspec.yaml
index a07777d8..675b4369 100644
--- a/built_value_test/pubspec.yaml
+++ b/built_value_test/pubspec.yaml
@@ -1,5 +1,5 @@
 name: built_value_test
-version: 8.12.5
+version: 8.12.6
 description: >
   Value types with builders, Dart classes as enums, and serialization.
   This library provides test support.
@@ -21,7 +21,7 @@ dependencies:
   quiver: '>=0.21.0 <4.0.0'
 
 dev_dependencies:
-  built_value_generator: ^8.12.5
+  built_value_generator: ^8.12.6
   build_runner: '>=1.0.0 <3.0.0'
   pedantic: ^1.4.0
   test: ^1.0.0
diff --git a/chat_example/pubspec.yaml b/chat_example/pubspec.yaml
index 3b6e4078..42147383 100644
--- a/chat_example/pubspec.yaml
+++ b/chat_example/pubspec.yaml
@@ -1,5 +1,5 @@
 name: chat_example
-version: 8.12.5
+version: 8.12.6
 publish_to: none
 description: >
   Just an example, not for publishing.
@@ -21,6 +21,6 @@ dev_dependencies:
   build_runner: any
   build_test: any
   build_web_compilers: any
-  built_value_generator: ^8.12.5
+  built_value_generator: ^8.12.6
   pedantic: ^1.4.0
   test: ^1.0.0
diff --git a/end_to_end_test/pubspec.yaml b/end_to_end_test/pubspec.yaml
index 9cbac1fe..16be1e4b 100644
--- a/end_to_end_test/pubspec.yaml
+++ b/end_to_end_test/pubspec.yaml
@@ -1,5 +1,5 @@
 name: end_to_end_test
-version: 8.12.5
+version: 8.12.6
 publish_to: none
 description: >
   Tests, not for publishing.
@@ -15,7 +15,7 @@ dependencies:
 dev_dependencies:
   build: '>=3.1.0 <5.0.0'
   build_runner: '>=2.5.0 <3.0.0'
-  built_value_generator: ^8.12.5
+  built_value_generator: ^8.12.6
   fixnum: ^1.0.0
   pedantic: ^1.4.0
   quiver: '>=0.21.0 <4.0.0'
diff --git a/example/pubspec.yaml b/example/pubspec.yaml
index d8bc6578..9244301f 100644
--- a/example/pubspec.yaml
+++ b/example/pubspec.yaml
@@ -13,7 +13,7 @@ dependencies:
 
 dev_dependencies:
   build_runner: '>=1.0.0 <3.0.0'
-  built_value_generator: ^8.12.5
+  built_value_generator: ^8.12.6
   pedantic: ^1.4.0
   quiver: '>=0.21.0 <4.0.0'
   test: ^1.0.0