diff --git a/src/crypto.h b/src/crypto.h
index 7aefd23..039771c 100644
--- a/src/crypto.h
+++ b/src/crypto.h
@@ -11,7 +11,7 @@ namespace horcrux {
 enum class Mode { kEncrypt, kDecrypt };
 
 class Cipher {
-protected:
+public:
     Cipher() = delete;
     explicit Cipher(Mode m) : mode(m) { }
     Cipher(Mode m, const std::vector<unsigned char>& key) :
@@ -20,6 +20,9 @@ protected:
     Cipher(Mode m, std::vector<unsigned char>&& key) :
         mode(m), encryption_key(key) {}
 
+    virtual ~Cipher() = default;
+
+protected:
     std::vector<unsigned char> encryption_key;
 
 public:
@@ -58,6 +61,8 @@ public:
             throw std::invalid_argument("Invalid key size");
     }
 
+    virtual ~AES256_CBC() = default;
+
     std::vector<unsigned char> process(
             const std::vector<unsigned char>& inputdata) override;
     std::vector<unsigned char> encrypt(
diff --git a/src/io.h b/src/io.h
index d355a58..096d850 100644
--- a/src/io.h
+++ b/src/io.h
@@ -10,16 +10,14 @@ namespace horcrux {
 
 class Input {
 public:
+    virtual ~Input() = default;
     virtual std::vector<unsigned char> read() = 0;
 };
 class Output {
 public:
+    virtual ~Output() = default;
     virtual size_t write(const std::vector<unsigned char>& data) = 0;
 };
-class PlainInput : public Input {};
-class CryptoInput : public Input {};
-class PlainOutput : public Output {};
-class CryptoOutput : public Output {};
 
 class FsPlainInput : public Input {
     std::filesystem::path file_path;
@@ -29,6 +27,7 @@ class FsPlainInput : public Input {
 
 public:
     explicit FsPlainInput(const std::string& path);
+    virtual ~FsPlainInput() = default;
     std::vector<unsigned char> read() override;
 };
 
@@ -39,6 +38,7 @@ class FsCryptoInput : public Input{
 
 public:
     explicit FsCryptoInput(const std::vector<std::string>& filenames);
+    virtual ~FsCryptoInput() = default;
     std::vector<unsigned char> read() override;
 };
 
@@ -48,6 +48,7 @@ class FsPlainOutput : public Output {
 
 public:
     explicit FsPlainOutput(const std::string& filename);
+    virtual ~FsPlainOutput() = default;
     size_t write(const std::vector<unsigned char>& to_write) override;
 };
 
@@ -64,6 +65,7 @@ public:
     FsCryptoOutput(const std::string& folder, const int horcrux_num,
                    const std::string& filename = "horcrux",
                    const size_t horcrux_size = 0);
+    virtual ~FsCryptoOutput() = default;
     size_t write(const std::vector<unsigned char>& to_write) override;
 };
 };  // namespace horcrux