SQL Server Error: A MERGE statement must be terminated by a semi-colon (;)

I have the following on a SQL Server 2014 database:

CREATE TABLE dbo.AssetGroupClassification  ( 
    ClassificationId    int IDENTITY(1,1) NOT NULL,
    ClassificationName  varchar(25) NOT NULL,
    CONSTRAINT [PK_AssetGroupClassification.ClassificationId] PRIMARY KEY CLUSTERED(ClassificationId)
)
GO
CREATE TYPE dbo.AssetGroupClassUDT AS TABLE (
    ClassificationId int IDENTITY (1, 1) NOT NULL, 
    ClassificationName varchar(25) NOT NULL
    )
GO

I'm attempting to create the below Stored Proc:

CREATE PROCEDURE dbo.AssetGroupClassUpsert
        @assetGrpClassData AssetGroupClassUDT READONLY
AS
BEGIN
    SET XACT_ABORT, NOCOUNT ON

    BEGIN TRY
        BEGIN TRANSACTION agcUpsertTran

        MERGE AssetGroupClassification AS t
        USING @assetGrpClassData AS src
        ON t.ClassificationId = src.ClassificationId
        WHEN MATCHED THEN
            UPDATE SET ClassificationName = src.ClassificationName
        WHEN NOT MATCHED THEN
            INSERT (ClassificationName)
            VALUES (src.ClassificationName);

        COMMIT TRANSACTION agcUpsertTran
    END TRY
    BEGIN CATCH
        IF @@trancount > 0 ROLLBACK TRANSACTION
        DECLARE @errMsg nvarchar(4000) = ERROR_MESSAGE()
        RAISERROR (@errMsg, 16, 1)

        RETURN 99   
    END CATCH
END
GO

However, I receive the error:

 A MERGE statement must be terminated by a semi-colon (;).

What am I missing? The semi-colon is clearly there so there must be something else up.