-# define _assert(ex) {if (!(ex)){fprintf(stderr,"Assertion failed: file %s, line %d\n", __FILE__, __LINE__);exit(1);}}
-# define assert(ex) {if (!(ex)){fprintf(stderr,"Assertion failed: file %s, line %d\n", __FILE__, __LINE__);exit(1);}}
+# define _assert(ex) {if (!(ex)){fprintf(stderr,"Assertion failed: file \"%s\", line %d\n", __FILE__, __LINE__);exit(1);}}
+# define assert(ex) _assert(ex)