"stray '#' in program assert" error when compiling

Question

I keep getting the above error message for blocks of code that use the assert function and I cannot see why this is. I have searched the Internet for potential answers to this error...without any success.

Below is the aforementioned block of code that throws up this error:

#include <stdio.h>
#include <assert.h>

typedef struct WORD
{
    char *Word;
    size_t Count;
    struct WORD *Left;
    struct WORD *Right;
} WORD;

#define SUCCESS                      0
#define NO_MEMORY_FOR_WORDNODE       3
#define NO_MEMORY_FOR_WORD           4

int AddToTree(WORD **DestTree, size_t *Treecount, char *Word)
{
    int Status = SUCCESS;
    int CompResult = 0;

    /* safety check */
    assert(NULL != DestTree);
    assert(NULL != Treecount);
    assert(NULL != Word);

    /* DestTree is NULL or it isn't */
    if(NULL == *DestTree){ /* this is the place to add it then */
        *DestTree = malloc(sizeof **DestTree);
        if(NULL == *DestTree){
            /* out of memory */
            Status = NO_MEMORY_FOR_WORDNODE;
        }
        else {
            (*DestTree)->Left = NULL;
            (*DestTree)->Right = NULL;
            (*DestTree)->Count = 1;
            (*DestTree)->Word = dupstr(Word);
            if(NULL == (*DestTree)->Word){
                /* out of memory in the middle */
                Status = NO_MEMORY_FOR_WORD;
                free(*DestTree);
                *DestTree = NULL;
            }
            else {
                /* everything worked, add one to the tree nodes count */
                ++*Treecount;
            }
        }
    }
    else { /* we need to make a decision */
        CompResult = strcmp(Word, (*DestTree)->Word);
        if(0 < CompResult){
            Status = AddToTree(&(*DestTree)->Left, Treecount, Word);
        }
        else if(0 > CompResult){
            Status = AddToTree(&(*DestTree)->Left, Treecount, Word);
        }
        else {
            /* add one to the count - this is the same node */
            ++(*DestTree)->Count;
        }
    }  /* end of else we need to make a decision */
    return Status;
}

Please note that each one of the assert lines throws up the same error.

I took alk's advice to check the preprocessor outputs and this is what I get:

# 2 "ex6-4.c" 2
# 1 "c:\\mingw\\include\\assert.h" 1 3
# 38 "c:\\mingw\\include\\assert.h" 3
void __attribute__((__cdecl__)) __attribute__ ((__nothrow__)) _assert (const ch
ar*, const char*, int) __attribute__ ((__noreturn__));
# 16 "ex6-4.c" 2`

I have to admit that this makes as much sense to me as the error in question.