diff --git a/crates/uplc/src/machine/runtime.rs b/crates/uplc/src/machine/runtime.rs
index 8dc0cb77..dc1aac87 100644
--- a/crates/uplc/src/machine/runtime.rs
+++ b/crates/uplc/src/machine/runtime.rs
@@ -162,8 +162,8 @@ impl DefaultFunction {
             DefaultFunction::Sha3_256 => 0,
             DefaultFunction::Blake2b_256 => 0,
             DefaultFunction::VerifyEd25519Signature => 0,
-            DefaultFunction::VerifyEcdsaSecp256k1Signature => todo!(),
-            DefaultFunction::VerifySchnorrSecp256k1Signature => todo!(),
+            DefaultFunction::VerifyEcdsaSecp256k1Signature => 0,
+            DefaultFunction::VerifySchnorrSecp256k1Signature => 0,
             DefaultFunction::AppendString => 0,
             DefaultFunction::EqualsString => 0,
             DefaultFunction::EncodeUtf8 => 0,
@@ -239,8 +239,8 @@ impl DefaultFunction {
             DefaultFunction::Sha3_256 => arg.expect_type(Type::ByteString),
             DefaultFunction::Blake2b_256 => arg.expect_type(Type::ByteString),
             DefaultFunction::VerifyEd25519Signature => arg.expect_type(Type::ByteString),
-            DefaultFunction::VerifyEcdsaSecp256k1Signature => todo!(),
-            DefaultFunction::VerifySchnorrSecp256k1Signature => todo!(),
+            DefaultFunction::VerifyEcdsaSecp256k1Signature => arg.expect_type(Type::ByteString),
+            DefaultFunction::VerifySchnorrSecp256k1Signature => arg.expect_type(Type::ByteString),
             DefaultFunction::AppendString => arg.expect_type(Type::String),
             DefaultFunction::EqualsString => arg.expect_type(Type::String),
             DefaultFunction::EncodeUtf8 => arg.expect_type(Type::String),