diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 956cc29..deaac20 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -1722,7 +1722,7 @@
 	 * "nr_cpus" or "1" means set the concurrency level to the CPU count.
 	 * If this cannot be determined, fall back to the default AG geometry.
 	 */
-	if (!strcmp(value, "nr_cpus"))
+	if (!value || !strcmp(value, "nr_cpus"))
 		optnum = 1;
 	else
 		optnum = getnum(value, opts, subopt);
@@ -1867,7 +1867,7 @@
 	 * "nr_cpus" or 1 means set the concurrency level to the CPU count.  If
 	 * this cannot be determined, fall back to the default computation.
 	 */
-	if (!strcmp(value, "nr_cpus"))
+	if (!value || !strcmp(value, "nr_cpus"))
 		optnum = 1;
 	else
 		optnum = getnum(value, opts, subopt);