diff --git a/arch/sparc/prom/bootstr_64.c b/arch/sparc/prom/bootstr_64.c
index ab9ccc63b388..7149e77714a4 100644
--- a/arch/sparc/prom/bootstr_64.c
+++ b/arch/sparc/prom/bootstr_64.c
@@ -14,7 +14,10 @@
  *          the .bss section or it will break things.
  */
 
-#define BARG_LEN  256
+/* We limit BARG_LEN to 1024 because this is the size of the
+ * 'barg_out' command line buffer in the SILO bootloader.
+ */
+#define BARG_LEN 1024
 struct {
 	int bootstr_len;
 	int bootstr_valid;