diff --git a/include/json/value.h b/include/json/value.h
index 1cd6291..b590825 100644
--- a/include/json/value.h
+++ b/include/json/value.h
@@ -35,15 +35,20 @@ namespace Json {
 
 /** Base class for all exceptions we throw.
  */
-class Exception : public std::exception {
-public:
-  Exception(std::string const& msg);
-  virtual ~Exception() throw();
-  virtual char const* what() const throw();
-protected:
-  std::string const& msg_;
-  void* future_use_;
-};
+class JSON_API Exception;
+/** Exceptions which the user cannot easily avoid.
+ *
+ * E.g. out-of-memory, stack-overflow, malicious input
+ */
+class JSON_API RuntimeError;
+/** Exceptions throw by JSON_ASSERT/JSON_FAIL macros.
+ *
+ * These are precondition-violations (user bugs) and internal errors (our bugs).
+ */
+class JSON_API LogicError;
+
+JSON_API void throwRuntimeError(std::string const& msg);
+JSON_API void throwLogicError(std::string const& msg);
 
 /** \brief Type of the value held by a Value object.
  */
diff --git a/src/lib_json/json_value.cpp b/src/lib_json/json_value.cpp
index f7d2cde..a71b0c1 100644
--- a/src/lib_json/json_value.cpp
+++ b/src/lib_json/json_value.cpp
@@ -152,17 +152,46 @@ static inline void releaseStringValue(char* value) { free(value); }
 
 namespace Json {
 
+class JSON_API Exception : public std::exception {
+public:
+  Exception(std::string const& msg);
+  virtual ~Exception() throw();
+  virtual char const* what() const throw();
+protected:
+  std::string const& msg_;
+};
+class JSON_API RuntimeError : public Exception {
+public:
+  RuntimeError(std::string const& msg);
+};
+class JSON_API LogicError : public Exception {
+public:
+  LogicError(std::string const& msg);
+};
+
 Exception::Exception(std::string const& msg)
   : msg_(msg)
-  , future_use_(NULL)
-{
-}
+{}
 Exception::~Exception() throw()
 {}
 char const* Exception::what() const throw()
 {
   return msg_.c_str();
 }
+RuntimeError::RuntimeError(std::string const& msg)
+  : Exception(msg)
+{}
+LogicError::LogicError(std::string const& msg)
+  : Exception(msg)
+{}
+void throwRuntimeError(std::string const& msg)
+{
+  throw RuntimeError(msg);
+}
+void throwLogicError(std::string const& msg)
+{
+  throw LogicError(msg);
+}
 
 // //////////////////////////////////////////////////////////////////
 // //////////////////////////////////////////////////////////////////