 
 		var resultLen: UInt32 = 0
 		let result = UnsafeMutablePointer<Byte>(allocatingCapacity: Int(EVP_MAX_MD_SIZE))
-		key.withUnsafeBufferPointer { keyPtr in
+		_ = key.withUnsafeBufferPointer { keyPtr in
 			message.withUnsafeBufferPointer { msgPtr in
 				COpenSSL.HMAC(type.evp, keyPtr.baseAddress, Int32(key.count), msgPtr.baseAddress, msgPtr.count, result, &resultLen)
 			}

			EVP_DigestUpdate(ctx, UnsafePointer<Void>(digestPtr.baseAddress), digestPtr.count)
			var signLen: UInt32 = 0
			var buf = Data.buffer(with: Int(EVP_PKEY_size(key.key)))
			buf.withUnsafeMutableBufferPointer { ptr in
				EVP_SignFinal(ctx, ptr.baseAddress, &signLen, key.key)
			}
			return Data(buf.prefix(Int(signLen)))

		OpenSSL.initialize()

		var hashBuf = Data.buffer(with: Int(type.digestLength))
		_ = message.withUnsafeBufferPointer { ptr in
			hashBuf.withUnsafeMutableBufferPointer { bufPtr in
				type.function(ptr.baseAddress, ptr.count, bufPtr.baseAddress)
			}
