Memory leak

I have a very simple routine to get the height and width of an XPM image:

void XpmImageConverter::getImageDimensions()
{
    gdImagePtr image;
    char tmpFilename[_fname.length() + 1];

    // GD doesn't like const pointers :(
    strcpy(tmpFilename, _fname.c_str());
    if ((image = gdImageCreateFromXpm(tmpFilename)) == NULL)
    {
        std::cerr << "Failed to open jpeg file \"" << _fname << "\"" << 
std::endl;
        return;
    }

    imageWidth = gdImageSX(image);
    imageHeight = gdImageSY(image);

    gdImageDestroy(image);
}

where imageWidth and imageHeight are unsigned int (class variable) and 
_fname is a std::string (class variable).

According to Valgrind, this is leaking a lot of memory (for small 
images, largest is 48x48 pixels, most are 24x24 pixels):
==16200== 32,731,968 bytes in 33 blocks are possibly lost in loss record 
744 of 744
==16200==    at 0x4005525: malloc (vg_replace_malloc.c:149)
==16200==    by 0xD9067A: xpmParseData (in /usr/lib/libXpm.so.4.11.0)
==16200==    by 0xD893B9: XpmReadFileToXpmImage (in 
/usr/lib/libXpm.so.4.11.0)
==16200==    by 0x80CBED5: gdImageCreateFromXpm (in )
==16200==    by 0x437E45F: XpmImageConverter::getImageDimensions() ()

This is on Fedora 8, gcc 4.1.2-33, gd 2.0.35, and libXpm 3.5.7.

Any ideas?  Restarting my app to free up the memory is kind of a pain.

- Brian