diff --git a/lib/src/keychain.dart b/lib/src/keychain.dart
index 975d0d0..8f17c97 100644
--- a/lib/src/keychain.dart
+++ b/lib/src/keychain.dart
@@ -32,7 +32,7 @@ class Keychain {
 
   /// Encapsulate dart-bip340 verify() so you don't need to add bip340 as a dependency
   static bool verify(
-    String? pubkey,
+    String pubkey,
     String message,
     String signature,
   ) {
diff --git a/pubspec.yaml b/pubspec.yaml
index f9f5cde..2b35ccb 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -10,7 +10,7 @@ dev_dependencies:
   lints: ^5.1.1
   test: ^1.16.0
 dependencies:
-  bip340: ^0.2.0
+  bip340: ^0.3.0
   convert: ^3.1.1
   pointycastle: ^3.7.3
   bech32: ^0.2.2