diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5f3f84efe..7ff77396b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@ This project uses the changelog in accordance with [keepchangelog](http://keepac
 ## [Unreleased][unreleased]
 ### Changed
 - Iclass read, `hf iclass read` now also reads tag config and prints configuration. (holiman)
+- *bootrom* needs to be flashed, due to new address boundaries between os and fpga, after a size optimization (piwi)
 
 ### Fixed
 - Fixed issue #19, problems with LF T55xx commands (marshmellow)
diff --git a/armsrc/iclass.c b/armsrc/iclass.c
index e5bd4f428..4d2f924c5 100644
--- a/armsrc/iclass.c
+++ b/armsrc/iclass.c
@@ -1676,7 +1676,8 @@ uint8_t handshakeIclassTag(uint8_t *card_data)
 // Reader iClass Anticollission
 void ReaderIClass(uint8_t arg0) {
 
-	uint8_t card_data[6 * 8]={0xFF};
+	uint8_t card_data[6 * 8]={0};
+	memset(card_data, 0xFF, sizeof(card_data));
     uint8_t last_csn[8]={0};
 	
 	//Read conf block CRC(0x01) => 0xfa 0x22