diff --git a/posixtz.c b/posixtz.c
index 141cca1..604a53d 100644
--- a/posixtz-0.3/posixtz.c
+++ b/posixtz-0.3/posixtz.c
@@ -25,18 +25,19 @@
 
 char *posix_tz(const char *filename)
 {
-	int fd, r;
+	FILE *f;
+	size_t r;
 	static char buf[TZ_BUFLEN];
 	char *p = NULL;
-	fd = open(filename, O_RDONLY);
-	if (fd < 0)
+	f = fopen(filename, "r");
+	if (f == NULL)
 		return NULL;
 	
-	r = read(fd, buf, TZ_BUFLEN);
+	r = fread(buf, 1, TZ_BUFLEN, f);
 	if (r != TZ_BUFLEN
 	    || strncmp(buf, "TZif", 4) != 0
 	    || (unsigned char)buf[4] < 2
-	    || lseek(fd, -TZ_BUFLEN, SEEK_END) < 0
+	    || fseek(f, -TZ_BUFLEN, SEEK_END) < 0
 	   )
 		goto ERROR;
 
@@ -50,7 +51,7 @@ char *posix_tz(const char *filename)
 	** (with nothing between the newlines if there is no POSIX representation for
 	** such instants).
 	*/
-	r = read(fd, buf, TZ_BUFLEN);
+	r = fread(buf, 1, TZ_BUFLEN, f);
 	if (r <= 0 || buf[--r] != '\n')
 		goto ERROR;
 	buf[r] = 0;
@@ -61,7 +62,7 @@ char *posix_tz(const char *filename)
 		}
 	} /* else ('\n' not found): p remains NULL */
 ERROR:
-	close(fd);
+	fclose(f);
 	return p;
 }