diff --git a/drivers/staging/greybus/firmware.h b/drivers/staging/greybus/firmware.h
index ec6bfb7f95c0..f4f0db1cefe8 100644
--- a/drivers/staging/greybus/firmware.h
+++ b/drivers/staging/greybus/firmware.h
@@ -14,7 +14,10 @@
 
 #define FW_NAME_PREFIX	"gmp_"
 
-/* Length of the string in format: "FW_NAME_PREFIX""%08x_%08x_%08x_%08x_%s.tftf" */
+/*
+ * Length of the string in format: "FW_NAME_PREFIX""%08x_%08x_%08x_%08x_%s.tftf"
+ *                                  (3 + 1 + 4 * (8 + 1) + 10 + 1 + 4 + 1)
+ */
 #define FW_NAME_SIZE		56
 
 /* Firmware Management Protocol specific functions */