Index: uspace/drv/bus/isa/isa.c
===================================================================
--- uspace/drv/bus/isa/isa.c	(revision 38d150e6238ab44c861f6486e46454e07caeb0f0)
+++ uspace/drv/bus/isa/isa.c	(revision bde5c044624f5375df5235c6f6f2f4a7286fbe1a)
@@ -277,5 +277,6 @@
 	int fd;
 	size_t len;
-	ssize_t r;
+	int rc;
+	size_t nread;
 	struct stat st;
 
@@ -306,11 +307,11 @@
 	}
 
-	r = vfs_read(fd, (aoff64_t []) {0}, buf, len);
-	if (r < 0) {
+	rc = vfs_read(fd, (aoff64_t []) {0}, buf, len, &nread);
+	if (rc != EOK) {
 		ddf_msg(LVL_ERROR, "Unable to read file '%s'.", conf_path);
 		goto cleanup;
 	}
 
-	buf[len] = 0;
+	buf[nread] = 0;
 
 	suc = true;