diff --git a/lib/src/charcode.dart b/lib/src/charcode.dart
new file mode 100644
index 0000000..d157749
--- /dev/null
+++ b/lib/src/charcode.dart
@@ -0,0 +1,24 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// Character '\'.
+const int $backslash = 0x5C;
+
+/// "Carriage return" control character.
+const int $cr = 0x0D;
+
+/// Character '"'.
+const int $doubleQuote = 0x22;
+
+/// Character 'f'.
+const int $f = 0x66;
+
+/// "Line feed" control character.
+const int $lf = 0x0A;
+
+/// Space character.
+const int $space = 0x20;
+
+/// Character 'x'.
+const int $x = 0x78;
diff --git a/lib/src/eager_span_scanner.dart b/lib/src/eager_span_scanner.dart
index 415b9f3..d27a818 100644
--- a/lib/src/eager_span_scanner.dart
+++ b/lib/src/eager_span_scanner.dart
@@ -2,8 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'package:charcode/ascii.dart';
-
+import 'charcode.dart';
 import 'line_scanner.dart';
 import 'span_scanner.dart';
 
diff --git a/lib/src/line_scanner.dart b/lib/src/line_scanner.dart
index 358d4c1..af6b6e7 100644
--- a/lib/src/line_scanner.dart
+++ b/lib/src/line_scanner.dart
@@ -2,8 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'package:charcode/ascii.dart';
-
+import 'charcode.dart';
 import 'string_scanner.dart';
 
 // Note that much of this code is duplicated in eager_span_scanner.dart.
diff --git a/lib/src/string_scanner.dart b/lib/src/string_scanner.dart
index 564774c..5d69c75 100644
--- a/lib/src/string_scanner.dart
+++ b/lib/src/string_scanner.dart
@@ -2,9 +2,9 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'package:charcode/charcode.dart';
 import 'package:source_span/source_span.dart';
 
+import 'charcode.dart';
 import 'exception.dart';
 import 'utils.dart';
 
@@ -110,7 +110,7 @@
     if (name == null) {
       if (character == $backslash) {
         name = r'"\"';
-      } else if (character == $double_quote) {
+      } else if (character == $doubleQuote) {
         name = r'"\""';
       } else {
         name = '"${String.fromCharCode(character)}"';
diff --git a/pubspec.yaml b/pubspec.yaml
index 0d29f2e..1b2c2e5 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -8,7 +8,6 @@
   sdk: ">=2.12.0-0 <3.0.0"
 
 dependencies:
-  charcode: '>=1.2.0-nullsafety <1.2.0'
   source_span: '>=1.8.0-nullsafety <1.8.0'
 
 dev_dependencies:
diff --git a/test/line_scanner_test.dart b/test/line_scanner_test.dart
index 0bbd499..a3deff1 100644
--- a/test/line_scanner_test.dart
+++ b/test/line_scanner_test.dart
@@ -2,7 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'package:charcode/charcode.dart';
+import 'package:string_scanner/src/charcode.dart';
 import 'package:string_scanner/string_scanner.dart';
 import 'package:test/test.dart';
 
diff --git a/test/string_scanner_test.dart b/test/string_scanner_test.dart
index 0327499..34176b8 100644
--- a/test/string_scanner_test.dart
+++ b/test/string_scanner_test.dart
@@ -2,7 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-import 'package:charcode/charcode.dart';
+import 'package:string_scanner/src/charcode.dart';
 import 'package:string_scanner/string_scanner.dart';
 import 'package:test/test.dart';