diff --git a/CHANGELOG.md b/CHANGELOG.md
index eeb000c..12e0105 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,3 @@
-## 0.12.7
-
-- Add `isAssertionError` matcher.
-
 ## 0.12.6
 
 - Update minimum Dart SDK to `2.2.0`.
diff --git a/lib/src/error_matchers.dart b/lib/src/error_matchers.dart
index 0153a70..5116975 100644
--- a/lib/src/error_matchers.dart
+++ b/lib/src/error_matchers.dart
@@ -40,6 +40,3 @@
 
 /// A matcher for [UnsupportedError].
 const isUnsupportedError = TypeMatcher<UnsupportedError>();
-
-/// A matcher for [AssertionError].
-const isAssertionError = TypeMatcher<AssertionError>();
diff --git a/pubspec.yaml b/pubspec.yaml
index b445f68..a65ec98 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: matcher
-version: 0.12.7
+version: 0.12.6
 
 description: >-
   Support for specifying test expectations via an extensible Matcher class.