Unknown type name 'bool', C++ / Xcode

Having trouble with this:

template<typename KeyType, typename ValueType>
class HashTable
{
public:
    HashTable(int numBuckets, int capacity);
    ~HashTable();

    bool isFull() const;
    bool set(const KeyType& key, const ValueType& value, bool permanent = false);   
}

The compiler error is on the line bool set..., reads unknown type name 'bool'. All that is pretty much just in some include guards with the rest of the implementation of the template class. I have no clue why the compiler no longer recognizes a built in type.