What's wrong with this code?

Code:

#include <stdio.h>

struct myStruct
{
  int a;
  int b;
};

int main(void)
{
  FILE* foo;
  struct myStruct bar;

  foo = fopen("foobar.txt", "rb");
  fread(&bar.a, 4, 1, foo);
  fclose(foo);
  printf("%d\n", bar.a);

  return 0;
}

The program generates a runtime exception when executing the fread() command. What's the correct way to do this?