Segmentation fault, how come?

I'm new to C and have stumbled over a problem I can't get a grip of.

I've written a function that reads floating point numbers from a file and put them in a allocated (malloc) match_t array. It works fine so far. But when writing a unit test for it (yes wrong order, I know), strange things happens.

Code:

typedef struct match_s {

    double home;
    double draw;
    double away;

} match_t; 
 	Code:
 	void test_readMatchStats() {
    
    int c;
    match_t *matchArray;
    match_t facit[] = {
        {0.11, 0.12, 0.13},
        {0.21, 0.22, 0.23},
        {0.31, 0.32, 0.33},
        {0.41, 0.42, 0.43},
        {0.51, 0.52, 0.53}
    };
    matchArray = readMatchStats("test.txt");
    ...
} 

When the facit array gets over 4 in legth I get a segmentation fault, otherwise it works. If I comment out the call to readMatchStats, I can make it bigger. Why is that?