diff --git a/wally/suits/io/check_linearity.cfg b/wally/suits/io/check_linearity.cfg
index f7c37fb..6af5fcc 100644
--- a/wally/suits/io/check_linearity.cfg
+++ b/wally/suits/io/check_linearity.cfg
@@ -6,6 +6,7 @@
 size={TEST_FILE_SIZE}
 ramp_time=5
 runtime=30
+BLOCK_SIZES={% 512,1k,2k,4k,8k,16k,32k,128k,256k,512k,1m %}
 
 # ---------------------------------------------------------------------
 # check read and write linearity. oper_time = func(size)