diff --git a/CHANGELOG.md b/CHANGELOG.md
index cbbd99d..dd62c40 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,10 @@
 # Flutter Scroll Shadow
 
+## [1.2.0] - 2023-04-10
+#### [@rickypid](https://github.com/rickypid)
+
+* Update SDK version.
+
 ## [1.1.0] - 2023-01-04
 #### [@rickypid](https://github.com/rickypid)
 - Improved documentations.
@@ -37,4 +42,4 @@
 
 ## [0.1.0-alpha] - 2021-04-30
 #### [@rickypid](https://github.com/rickypid)
-- Initial release.
+- Initial release.
\ No newline at end of file
diff --git a/example/pubspec.lock b/example/pubspec.lock
index 7573d32..e50b801 100644
--- a/example/pubspec.lock
+++ b/example/pubspec.lock
@@ -5,49 +5,56 @@ packages:
     dependency: transitive
     description:
       name: args
-      url: "https://pub.dartlang.org"
+      sha256: b003c3098049a51720352d219b0bb5f219b60fbfb68e7a4748139a06a5676515
+      url: "https://pub.dev"
     source: hosted
     version: "2.3.1"
   async:
     dependency: transitive
     description:
       name: async
-      url: "https://pub.dartlang.org"
+      sha256: bfe67ef28df125b7dddcea62755991f807aa39a2492a23e1550161692950bbe0
+      url: "https://pub.dev"
     source: hosted
-    version: "2.9.0"
+    version: "2.10.0"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
-      url: "https://pub.dartlang.org"
+      sha256: "6cfb5af12253eaf2b368f07bacc5a80d1301a071c73360d746b7f2e32d762c66"
+      url: "https://pub.dev"
     source: hosted
-    version: "2.1.0"
+    version: "2.1.1"
   characters:
     dependency: transitive
     description:
       name: characters
-      url: "https://pub.dartlang.org"
+      sha256: e6a326c8af69605aec75ed6c187d06b349707a27fbff8222ca9cc2cff167975c
+      url: "https://pub.dev"
     source: hosted
     version: "1.2.1"
   clock:
     dependency: transitive
     description:
       name: clock
-      url: "https://pub.dartlang.org"
+      sha256: cb6d7f03e1de671e34607e909a7213e31d7752be4fb66a86d29fe1eb14bfb5cf
+      url: "https://pub.dev"
     source: hosted
     version: "1.1.1"
   collection:
     dependency: transitive
     description:
       name: collection
-      url: "https://pub.dartlang.org"
+      sha256: cfc915e6923fe5ce6e153b0723c753045de46de1b4d63771530504004a45fae0
+      url: "https://pub.dev"
     source: hosted
-    version: "1.16.0"
+    version: "1.17.0"
   fake_async:
     dependency: transitive
     description:
       name: fake_async
-      url: "https://pub.dartlang.org"
+      sha256: "511392330127add0b769b75a987850d136345d9227c6b94c96a04cf4a391bf78"
+      url: "https://pub.dev"
     source: hosted
     version: "1.3.1"
   flutter:
@@ -59,7 +66,8 @@ packages:
     dependency: "direct dev"
     description:
       name: flutter_lints
-      url: "https://pub.dartlang.org"
+      sha256: aeb0b80a8b3709709c9cc496cdc027c5b3216796bc0af0ce1007eaf24464fd4c
+      url: "https://pub.dev"
     source: hosted
     version: "2.0.1"
   flutter_scroll_shadow:
@@ -68,7 +76,7 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "1.1.0"
+    version: "1.2.0"
   flutter_test:
     dependency: "direct dev"
     description: flutter
@@ -78,42 +86,56 @@ packages:
     dependency: "direct dev"
     description:
       name: import_sorter
-      url: "https://pub.dartlang.org"
+      sha256: eb15738ccead84e62c31e0208ea4e3104415efcd4972b86906ca64a1187d0836
+      url: "https://pub.dev"
     source: hosted
     version: "4.6.0"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      sha256: "5528c2f391ededb7775ec1daa69e65a2d61276f7552de2b5f7b8d34ee9fd4ab7"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.6.5"
   lints:
     dependency: transitive
     description:
       name: lints
-      url: "https://pub.dartlang.org"
+      sha256: "5e4a9cd06d447758280a8ac2405101e0e2094d2a1dbdd3756aec3fe7775ba593"
+      url: "https://pub.dev"
     source: hosted
     version: "2.0.1"
   matcher:
     dependency: transitive
     description:
       name: matcher
-      url: "https://pub.dartlang.org"
+      sha256: "16db949ceee371e9b99d22f88fa3a73c4e59fd0afed0bd25fc336eb76c198b72"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.12.12"
+    version: "0.12.13"
   material_color_utilities:
     dependency: transitive
     description:
       name: material_color_utilities
-      url: "https://pub.dartlang.org"
+      sha256: d92141dc6fe1dad30722f9aa826c7fbc896d021d792f80678280601aff8cf724
+      url: "https://pub.dev"
     source: hosted
-    version: "0.1.5"
+    version: "0.2.0"
   meta:
     dependency: transitive
     description:
       name: meta
-      url: "https://pub.dartlang.org"
+      sha256: "6c268b42ed578a53088d834796959e4a1814b5e9e164f147f580a386e5decf42"
+      url: "https://pub.dev"
     source: hosted
     version: "1.8.0"
   path:
     dependency: transitive
     description:
       name: path
-      url: "https://pub.dartlang.org"
+      sha256: db9d4f58c908a4ba5953fcee2ae317c94889433e5024c27ce74a37f94267945b
+      url: "https://pub.dev"
     source: hosted
     version: "1.8.2"
   sky_engine:
@@ -125,65 +147,74 @@ packages:
     dependency: transitive
     description:
       name: source_span
-      url: "https://pub.dartlang.org"
+      sha256: dd904f795d4b4f3b870833847c461801f6750a9fa8e61ea5ac53f9422b31f250
+      url: "https://pub.dev"
     source: hosted
-    version: "1.9.0"
+    version: "1.9.1"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
-      url: "https://pub.dartlang.org"
+      sha256: c3c7d8edb15bee7f0f74debd4b9c5f3c2ea86766fe4178eb2a18eb30a0bdaed5
+      url: "https://pub.dev"
     source: hosted
-    version: "1.10.0"
+    version: "1.11.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
-      url: "https://pub.dartlang.org"
+      sha256: "83615bee9045c1d322bbbd1ba209b7a749c2cbcdcb3fdd1df8eb488b3279c1c8"
+      url: "https://pub.dev"
     source: hosted
-    version: "2.1.0"
+    version: "2.1.1"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
-      url: "https://pub.dartlang.org"
+      sha256: "556692adab6cfa87322a115640c11f13cb77b3f076ddcc5d6ae3c20242bedcde"
+      url: "https://pub.dev"
     source: hosted
-    version: "1.1.1"
+    version: "1.2.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
-      url: "https://pub.dartlang.org"
+      sha256: a29248a84fbb7c79282b40b8c72a1209db169a2e0542bce341da992fe1bc7e84
+      url: "https://pub.dev"
     source: hosted
     version: "1.2.1"
   test_api:
     dependency: transitive
     description:
       name: test_api
-      url: "https://pub.dartlang.org"
+      sha256: ad540f65f92caa91bf21dfc8ffb8c589d6e4dc0c2267818b4cc2792857706206
+      url: "https://pub.dev"
     source: hosted
-    version: "0.4.12"
+    version: "0.4.16"
   tint:
     dependency: transitive
     description:
       name: tint
-      url: "https://pub.dartlang.org"
+      sha256: d856019547532d4ea24171f554b319081c004c37741e7946eae30cb09f24e1c7
+      url: "https://pub.dev"
     source: hosted
     version: "2.0.0"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
-      url: "https://pub.dartlang.org"
+      sha256: "80b3257d1492ce4d091729e3a67a60407d227c27241d6927be0130c98e741803"
+      url: "https://pub.dev"
     source: hosted
-    version: "2.1.2"
+    version: "2.1.4"
   yaml:
     dependency: transitive
     description:
       name: yaml
-      url: "https://pub.dartlang.org"
+      sha256: "23812a9b125b48d4007117254bca50abb6c712352927eece9e155207b1db2370"
+      url: "https://pub.dev"
     source: hosted
     version: "3.1.1"
 sdks:
-  dart: ">=2.18.2 <3.0.0"
+  dart: ">=2.19.6 <3.0.0"
   flutter: ">=1.17.0"
diff --git a/example/pubspec.yaml b/example/pubspec.yaml
index 1128405..b91335e 100644
--- a/example/pubspec.yaml
+++ b/example/pubspec.yaml
@@ -1,10 +1,10 @@
 name: flutter_scroll_shadow_example
 description: A demonstration of the ScrollShadow widget for a scrollable child.
-version: 1.1.0
+version: 1.2.0
 publish_to: 'none'
 
 environment:
-  sdk: ">=2.18.2 <3.0.0"
+  sdk: '>=2.19.6 <3.0.0'
   flutter: ">=1.17.0"
 
 dependencies:
@@ -20,4 +20,4 @@ dev_dependencies:
   import_sorter: ^4.6.0
 
 flutter:
-  uses-material-design: true
+  uses-material-design: true
\ No newline at end of file
diff --git a/lib/src/scroll_shadow.dart b/lib/src/scroll_shadow.dart
index 6069789..95b917e 100644
--- a/lib/src/scroll_shadow.dart
+++ b/lib/src/scroll_shadow.dart
@@ -117,8 +117,7 @@ class _ScrollShadowState extends State<ScrollShadow> {
     if (widget.controller != null) {
       _controller = widget.controller!..addListener(_listener);
     } else if (_controller != PrimaryScrollController.of(context)) {
-      _controller = PrimaryScrollController.of(context)!
-        ..addListener(_listener);
+      _controller = PrimaryScrollController.of(context)..addListener(_listener);
     }
     _update();
 
diff --git a/pubspec.lock b/pubspec.lock
index 08efd35..6f2d0ae 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -5,49 +5,56 @@ packages:
     dependency: transitive
     description:
       name: args
-      url: "https://pub.dartlang.org"
+      sha256: b003c3098049a51720352d219b0bb5f219b60fbfb68e7a4748139a06a5676515
+      url: "https://pub.dev"
     source: hosted
     version: "2.3.1"
   async:
     dependency: transitive
     description:
       name: async
-      url: "https://pub.dartlang.org"
+      sha256: bfe67ef28df125b7dddcea62755991f807aa39a2492a23e1550161692950bbe0
+      url: "https://pub.dev"
     source: hosted
-    version: "2.9.0"
+    version: "2.10.0"
   boolean_selector:
     dependency: transitive
     description:
       name: boolean_selector
-      url: "https://pub.dartlang.org"
+      sha256: "6cfb5af12253eaf2b368f07bacc5a80d1301a071c73360d746b7f2e32d762c66"
+      url: "https://pub.dev"
     source: hosted
-    version: "2.1.0"
+    version: "2.1.1"
   characters:
     dependency: transitive
     description:
       name: characters
-      url: "https://pub.dartlang.org"
+      sha256: e6a326c8af69605aec75ed6c187d06b349707a27fbff8222ca9cc2cff167975c
+      url: "https://pub.dev"
     source: hosted
     version: "1.2.1"
   clock:
     dependency: transitive
     description:
       name: clock
-      url: "https://pub.dartlang.org"
+      sha256: cb6d7f03e1de671e34607e909a7213e31d7752be4fb66a86d29fe1eb14bfb5cf
+      url: "https://pub.dev"
     source: hosted
     version: "1.1.1"
   collection:
     dependency: transitive
     description:
       name: collection
-      url: "https://pub.dartlang.org"
+      sha256: cfc915e6923fe5ce6e153b0723c753045de46de1b4d63771530504004a45fae0
+      url: "https://pub.dev"
     source: hosted
-    version: "1.16.0"
+    version: "1.17.0"
   fake_async:
     dependency: transitive
     description:
       name: fake_async
-      url: "https://pub.dartlang.org"
+      sha256: "511392330127add0b769b75a987850d136345d9227c6b94c96a04cf4a391bf78"
+      url: "https://pub.dev"
     source: hosted
     version: "1.3.1"
   flutter:
@@ -59,7 +66,8 @@ packages:
     dependency: "direct dev"
     description:
       name: flutter_lints
-      url: "https://pub.dartlang.org"
+      sha256: aeb0b80a8b3709709c9cc496cdc027c5b3216796bc0af0ce1007eaf24464fd4c
+      url: "https://pub.dev"
     source: hosted
     version: "2.0.1"
   flutter_test:
@@ -71,42 +79,56 @@ packages:
     dependency: "direct dev"
     description:
       name: import_sorter
-      url: "https://pub.dartlang.org"
+      sha256: eb15738ccead84e62c31e0208ea4e3104415efcd4972b86906ca64a1187d0836
+      url: "https://pub.dev"
     source: hosted
     version: "4.6.0"
+  js:
+    dependency: transitive
+    description:
+      name: js
+      sha256: "5528c2f391ededb7775ec1daa69e65a2d61276f7552de2b5f7b8d34ee9fd4ab7"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.6.5"
   lints:
     dependency: transitive
     description:
       name: lints
-      url: "https://pub.dartlang.org"
+      sha256: "5e4a9cd06d447758280a8ac2405101e0e2094d2a1dbdd3756aec3fe7775ba593"
+      url: "https://pub.dev"
     source: hosted
     version: "2.0.1"
   matcher:
     dependency: transitive
     description:
       name: matcher
-      url: "https://pub.dartlang.org"
+      sha256: "16db949ceee371e9b99d22f88fa3a73c4e59fd0afed0bd25fc336eb76c198b72"
+      url: "https://pub.dev"
     source: hosted
-    version: "0.12.12"
+    version: "0.12.13"
   material_color_utilities:
     dependency: transitive
     description:
       name: material_color_utilities
-      url: "https://pub.dartlang.org"
+      sha256: d92141dc6fe1dad30722f9aa826c7fbc896d021d792f80678280601aff8cf724
+      url: "https://pub.dev"
     source: hosted
-    version: "0.1.5"
+    version: "0.2.0"
   meta:
     dependency: transitive
     description:
       name: meta
-      url: "https://pub.dartlang.org"
+      sha256: "6c268b42ed578a53088d834796959e4a1814b5e9e164f147f580a386e5decf42"
+      url: "https://pub.dev"
     source: hosted
     version: "1.8.0"
   path:
     dependency: transitive
     description:
       name: path
-      url: "https://pub.dartlang.org"
+      sha256: db9d4f58c908a4ba5953fcee2ae317c94889433e5024c27ce74a37f94267945b
+      url: "https://pub.dev"
     source: hosted
     version: "1.8.2"
   sky_engine:
@@ -118,65 +140,74 @@ packages:
     dependency: transitive
     description:
       name: source_span
-      url: "https://pub.dartlang.org"
+      sha256: dd904f795d4b4f3b870833847c461801f6750a9fa8e61ea5ac53f9422b31f250
+      url: "https://pub.dev"
     source: hosted
-    version: "1.9.0"
+    version: "1.9.1"
   stack_trace:
     dependency: transitive
     description:
       name: stack_trace
-      url: "https://pub.dartlang.org"
+      sha256: c3c7d8edb15bee7f0f74debd4b9c5f3c2ea86766fe4178eb2a18eb30a0bdaed5
+      url: "https://pub.dev"
     source: hosted
-    version: "1.10.0"
+    version: "1.11.0"
   stream_channel:
     dependency: transitive
     description:
       name: stream_channel
-      url: "https://pub.dartlang.org"
+      sha256: "83615bee9045c1d322bbbd1ba209b7a749c2cbcdcb3fdd1df8eb488b3279c1c8"
+      url: "https://pub.dev"
     source: hosted
-    version: "2.1.0"
+    version: "2.1.1"
   string_scanner:
     dependency: transitive
     description:
       name: string_scanner
-      url: "https://pub.dartlang.org"
+      sha256: "556692adab6cfa87322a115640c11f13cb77b3f076ddcc5d6ae3c20242bedcde"
+      url: "https://pub.dev"
     source: hosted
-    version: "1.1.1"
+    version: "1.2.0"
   term_glyph:
     dependency: transitive
     description:
       name: term_glyph
-      url: "https://pub.dartlang.org"
+      sha256: a29248a84fbb7c79282b40b8c72a1209db169a2e0542bce341da992fe1bc7e84
+      url: "https://pub.dev"
     source: hosted
     version: "1.2.1"
   test_api:
     dependency: transitive
     description:
       name: test_api
-      url: "https://pub.dartlang.org"
+      sha256: ad540f65f92caa91bf21dfc8ffb8c589d6e4dc0c2267818b4cc2792857706206
+      url: "https://pub.dev"
     source: hosted
-    version: "0.4.12"
+    version: "0.4.16"
   tint:
     dependency: transitive
     description:
       name: tint
-      url: "https://pub.dartlang.org"
+      sha256: d856019547532d4ea24171f554b319081c004c37741e7946eae30cb09f24e1c7
+      url: "https://pub.dev"
     source: hosted
     version: "2.0.0"
   vector_math:
     dependency: transitive
     description:
       name: vector_math
-      url: "https://pub.dartlang.org"
+      sha256: "80b3257d1492ce4d091729e3a67a60407d227c27241d6927be0130c98e741803"
+      url: "https://pub.dev"
     source: hosted
-    version: "2.1.2"
+    version: "2.1.4"
   yaml:
     dependency: transitive
     description:
       name: yaml
-      url: "https://pub.dartlang.org"
+      sha256: "23812a9b125b48d4007117254bca50abb6c712352927eece9e155207b1db2370"
+      url: "https://pub.dev"
     source: hosted
     version: "3.1.1"
 sdks:
-  dart: ">=2.18.2 <3.0.0"
+  dart: ">=2.19.6 <3.0.0"
   flutter: ">=1.17.0"
diff --git a/pubspec.yaml b/pubspec.yaml
index 3b42cbf..84f6d2e 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,6 +1,6 @@
 name: flutter_scroll_shadow
 description: ScrollShadow adds shadows to a scrollable child. Supports ScrollController and vertical or horizontal orientation.
-version: 1.1.0
+version: 1.2.0
 repository: https://github.com/rickypid/flutter_scroll_shadow
 issue_tracker: https://github.com/rickypid/flutter_scroll_shadow/issues
 homepage: https://github.com/rickypid/flutter_scroll_shadow
@@ -8,7 +8,7 @@ documentation: https://github.com/rickypid/flutter_scroll_shadow#readme
 
 
 environment:
-  sdk: ">=2.18.2 <3.0.0"
+  sdk: '>=2.19.6 <3.0.0'
   flutter: ">=1.17.0"
 
 dependencies:
@@ -21,4 +21,4 @@ dev_dependencies:
   flutter_lints: ^2.0.1
   import_sorter: ^4.6.0
 
-flutter:
+flutter:
\ No newline at end of file