diff --git a/arch/powerpc/include/asm/rtas-types.h b/arch/powerpc/include/asm/rtas-types.h
index 9d5b16803cbb..5d40d187b965 100644
--- a/arch/powerpc/include/asm/rtas-types.h
+++ b/arch/powerpc/include/asm/rtas-types.h
@@ -42,8 +42,9 @@ struct rtas_error_log {
 	 */
 	u8		byte3;			/* General event or error*/
 	__be32		extended_log_length;	/* length in bytes */
-	unsigned char	buffer[1];		/* Start of extended log */
-						/* Variable length.      */
+
+	/* Start of extended log, variable length */
+	unsigned char	buffer[] __counted_by_be(extended_log_length);
 };
 
 /* RTAS general extended event log, Version 6. The extended log starts