diff --git a/common/exceptions/index_exception.hpp b/common/exceptions/index_exception.hpp
index f49d1c1..568aa30 100644
--- a/common/exceptions/index_exception.hpp
+++ b/common/exceptions/index_exception.hpp
@@ -4,9 +4,7 @@
 namespace nkg::exceptions {
 
     class index_exception : public ::nkg::exception {
-    public:
-        index_exception(std::string_view file, int line, std::string_view message) noexcept :
-            ::nkg::exception(file, line, message) {}
+        using ::nkg::exception::exception;
     };
 
 }
diff --git a/common/exceptions/key_exception.hpp b/common/exceptions/key_exception.hpp
index 6809748..933f8e1 100644
--- a/common/exceptions/key_exception.hpp
+++ b/common/exceptions/key_exception.hpp
@@ -4,9 +4,7 @@
 namespace nkg::exceptions {
 
     class key_exception : public ::nkg::exception {
-    public:
-        key_exception(std::string_view file, int line, std::string_view message) noexcept :
-            ::nkg::exception(file, line, message) {}
+        using ::nkg::exception::exception;
     };
 
 }
diff --git a/common/exceptions/operation_canceled_exception.hpp b/common/exceptions/operation_canceled_exception.hpp
index 5a1053c..b395175 100644
--- a/common/exceptions/operation_canceled_exception.hpp
+++ b/common/exceptions/operation_canceled_exception.hpp
@@ -4,9 +4,7 @@
 namespace nkg::exceptions {
 
     class operation_canceled_exception : public ::nkg::exception {
-    public:
-        operation_canceled_exception(std::string_view file, int line, std::string_view message) noexcept :
-            ::nkg::exception(file, line, message) {}
+        using ::nkg::exception::exception;
     };
 
 }
diff --git a/common/rsa_cipher.hpp b/common/rsa_cipher.hpp
index 8f0c212..df13e9d 100644
--- a/common/rsa_cipher.hpp
+++ b/common/rsa_cipher.hpp
@@ -17,42 +17,8 @@ namespace nkg {
 
     class rsa_cipher {
     public:
-        class no_key_assigned_error : public ::nkg::exception {
-        public:
-            no_key_assigned_error(std::string_view file, int line, std::string_view message) noexcept :
-                ::nkg::exception(file, line, message) {}
-        };
-
-        class backend_error : public ::nkg::exception {
-        public:
-            using error_code_t = decltype(ERR_get_error());
-
-        private:
-            std::optional<error_code_t> m_error_code;
-            std::string m_error_string;
-
-        public:
-            backend_error(std::string_view file, int line, std::string_view message) noexcept :
-                ::nkg::exception(file, line, message) {}
-
-            backend_error(std::string_view file, int line, error_code_t openssl_errno, std::string_view message) noexcept :
-                ::nkg::exception(file, line, message), m_error_code(openssl_errno) {}
-
-            [[nodiscard]]
-            virtual bool error_code_exists() const noexcept override {
-                return m_error_code.has_value();
-            }
-
-            [[nodiscard]]
-            virtual intptr_t error_code() const noexcept override {
-                if (error_code_exists()) { return m_error_code.value(); } else { trap_then_terminate(); }
-            }
-
-            [[nodiscard]]
-            virtual const std::string& error_string() const noexcept override {
-                if (error_code_exists()) { return m_error_string; } else { trap_then_terminate(); }
-            }
-        };
+        class backend_error;
+        class no_key_assigned_error;
 
     private:
         resource_wrapper<resource_traits::openssl::rsa> m_rsa;
@@ -73,7 +39,6 @@ namespace nkg {
         static void _write_public_key_pkcs1_to_bio(RSA* p_rsa, BIO* p_bio);
 
     public:
-
         rsa_cipher();
 
         [[nodiscard]]
@@ -117,6 +82,41 @@ namespace nkg {
         size_t private_decrypt(const void* ciphertext, size_t ciphertext_size, void* plaintext, int padding) const;
     };
 
+    class rsa_cipher::backend_error : public ::nkg::exception {
+    public:
+        using error_code_t = decltype(ERR_get_error());
+
+    private:
+        std::optional<error_code_t> m_error_code;
+        std::string m_error_string;
+
+    public:
+        backend_error(std::string_view file, int line, std::string_view message) noexcept :
+            ::nkg::exception(file, line, message) {}
+
+        backend_error(std::string_view file, int line, error_code_t openssl_errno, std::string_view message) noexcept :
+            ::nkg::exception(file, line, message), m_error_code(openssl_errno) {}
+
+        [[nodiscard]]
+        virtual bool error_code_exists() const noexcept override {
+            return m_error_code.has_value();
+        }
+
+        [[nodiscard]]
+        virtual intptr_t error_code() const noexcept override {
+            if (error_code_exists()) { return m_error_code.value(); } else { trap_then_terminate(); }
+        }
+
+        [[nodiscard]]
+        virtual const std::string& error_string() const noexcept override {
+            if (error_code_exists()) { return m_error_string; } else { trap_then_terminate(); }
+        }
+    };
+
+    class rsa_cipher::no_key_assigned_error : public ::nkg::exception {
+        using ::nkg::exception::exception;
+    };
+
 }
 
 #undef NKG_CURRENT_SOURCE_FILE
diff --git a/navicat-keygen/base32_rfc4648.hpp b/navicat-keygen/base32_rfc4648.hpp
index 530c0d9..f00d846 100644
--- a/navicat-keygen/base32_rfc4648.hpp
+++ b/navicat-keygen/base32_rfc4648.hpp
@@ -11,11 +11,7 @@ namespace nkg {
         static constexpr const char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567";
         static constexpr const char padding_character = '=';
 
-        class decoding_error : public ::nkg::exception {
-        public:
-            decoding_error(std::string_view file, int line, std::string_view message) noexcept :
-                ::nkg::exception(file, line, message) {}
-        };
+        class decoding_error;
 
         static char symbol(alphabet_index_t idx);
 
@@ -28,4 +24,8 @@ namespace nkg {
         static std::vector<uint8_t> decode(std::string_view b32_string);
     };
 
+    class base32_rfc4648::decoding_error : public ::nkg::exception {
+        using ::nkg::exception::exception;
+    };
+
 }
diff --git a/navicat-keygen/base64_rfc4648.hpp b/navicat-keygen/base64_rfc4648.hpp
index a67b435..8f7e0de 100644
--- a/navicat-keygen/base64_rfc4648.hpp
+++ b/navicat-keygen/base64_rfc4648.hpp
@@ -6,15 +6,15 @@
 namespace nkg {
 
     struct base64_rfc4648 {
-        class backend_error : public ::nkg::exception {
-        public:
-            backend_error(std::string_view file, int line, std::string_view message) noexcept :
-                ::nkg::exception(file, line, message) {}
-        };
+        class backend_error;
 
         static std::string encode(const std::vector<std::uint8_t>& data);
 
         static std::vector<uint8_t> decode(std::string_view str_b64);
     };
 
+    class base64_rfc4648::backend_error : public ::nkg::exception {
+        using ::nkg::exception::exception;
+    };
+
 }
diff --git a/navicat-keygen/navicat_serial_generator.hpp b/navicat-keygen/navicat_serial_generator.hpp
index d086132..75e6a06 100644
--- a/navicat-keygen/navicat_serial_generator.hpp
+++ b/navicat-keygen/navicat_serial_generator.hpp
@@ -35,11 +35,7 @@ namespace nkg {
 
     class navicat_serial_generator {
     public:
-        class version_error : public ::nkg::exception {
-        public:
-            version_error(std::string_view file, int line, std::string_view message) noexcept :
-                ::nkg::exception(file, line, message) {}
-        };
+        class version_error;
 
     private:
         static inline const DES_cblock s_des_key0 = { 0x64, 0xAD, 0xF3, 0x2F, 0xAE, 0xF2, 0x1A, 0x27 };
@@ -72,4 +68,8 @@ namespace nkg {
         const std::string& serial_number_formatted() const noexcept;
     };
 
+    class navicat_serial_generator::version_error : public ::nkg::exception {
+        using ::nkg::exception::exception;
+    };
+
 }
diff --git a/navicat-patcher/elf64_interpreter.hpp b/navicat-patcher/elf64_interpreter.hpp
index 377f0d3..7ef73b8 100644
--- a/navicat-patcher/elf64_interpreter.hpp
+++ b/navicat-patcher/elf64_interpreter.hpp
@@ -18,23 +18,9 @@ namespace nkg {
         using rva_t = uintptr_t;
         using va_t = uintptr_t;
 
-        class parse_error : public ::nkg::exception {
-        public:
-            parse_error(std::string_view file, int line, std::string_view message) noexcept :
-                ::nkg::exception(file, line, message) {}
-        };
-
-        class bad_fo_exception : public ::nkg::exception {
-        public:
-            bad_fo_exception(std::string_view file, int line, std::string_view message) noexcept :
-                ::nkg::exception(file, line, message) {}
-        };
-
-        class bad_va_exception : public ::nkg::exception {
-        public:
-            bad_va_exception(std::string_view file, int line, std::string_view message) noexcept :
-                ::nkg::exception(file, line, message) {}
-        };
+        class parse_error;
+        class bad_fo_exception;
+        class bad_va_exception;
 
     private:
         size_t m_elf_size;
@@ -236,4 +222,16 @@ namespace nkg {
         const std::map<va_t, size_t>& relocation_distribute() const;
     };
 
+    class elf64_interpreter::parse_error : public ::nkg::exception {
+        using ::nkg::exception::exception;
+    };
+
+    class elf64_interpreter::bad_fo_exception : public ::nkg::exception {
+        using ::nkg::exception::exception;
+    };
+
+    class elf64_interpreter::bad_va_exception : public ::nkg::exception {
+        using ::nkg::exception::exception;
+    };
+
 }
diff --git a/navicat-patcher/keystone_assembler.hpp b/navicat-patcher/keystone_assembler.hpp
index 60a910c..9f7ab6a 100644
--- a/navicat-patcher/keystone_assembler.hpp
+++ b/navicat-patcher/keystone_assembler.hpp
@@ -12,33 +12,7 @@ namespace nkg {
 
     class keystone_assembler {
     public:
-        class backend_error : public ::nkg::exception {
-        public:
-            using error_code_t = ks_err;
-
-        private:
-            error_code_t m_error_code;
-            std::string m_error_string;
-
-        public:
-            backend_error(std::string_view file, int line, error_code_t keystone_err, std::string_view message) noexcept :
-                ::nkg::exception(file, line, message), m_error_code(keystone_err), m_error_string(ks_strerror(keystone_err)) {}
-
-            [[nodiscard]]
-            virtual bool error_code_exists() const noexcept override {
-                return true;
-            }
-
-            [[nodiscard]]
-            virtual intptr_t error_code() const noexcept override {
-                return m_error_code;
-            }
-
-            [[nodiscard]]
-            virtual const std::string& error_string() const noexcept override {
-                return m_error_string;
-            }
-        };
+        class backend_error;
 
     private:
         resource_wrapper<resource_traits::keystone::keystone_handle> m_keystone_engine;
@@ -52,4 +26,32 @@ namespace nkg {
         std::vector<uint8_t> assemble(std::string_view asm_string, uint64_t asm_address = 0) const;
     };
 
+    class keystone_assembler::backend_error : public ::nkg::exception {
+    public:
+        using error_code_t = ks_err;
+
+    private:
+        error_code_t m_error_code;
+        std::string m_error_string;
+
+    public:
+        backend_error(std::string_view file, int line, error_code_t keystone_err, std::string_view message) noexcept :
+            ::nkg::exception(file, line, message), m_error_code(keystone_err), m_error_string(ks_strerror(keystone_err)) {}
+
+        [[nodiscard]]
+        virtual bool error_code_exists() const noexcept override {
+            return true;
+        }
+
+        [[nodiscard]]
+        virtual intptr_t error_code() const noexcept override {
+            return m_error_code;
+        }
+
+        [[nodiscard]]
+        virtual const std::string& error_string() const noexcept override {
+            return m_error_string;
+        }
+    };
+
 }