diff --git a/tools/benchmark.sh b/tools/benchmark.sh
index e0f252219cfccdcec4898e5095fc055e499332a6..a9e093776c619eb749dee8dcf7517351f8eafe59 100755
--- a/tools/benchmark.sh
+++ b/tools/benchmark.sh
@@ -290,7 +290,8 @@ level_const_params="
   $hard_pending_arg \
 "
 
-# TODO: these inherit level_const_params because the non-blob LSM tree uses leveled compaction
+# These inherit level_const_params because the non-blob LSM tree uses leveled compaction.
+# The use of undefok is for options that are not supported until 7.5.
 blob_const_params="
   $level_const_params \
   --enable_blob_files=true \
@@ -305,6 +306,7 @@ blob_const_params="
   --use_shared_block_and_blob_cache=$use_shared_block_and_blob_cache \
   --blob_cache_size=$blob_cache_size \
   --blob_cache_numshardbits=$blob_cache_numshardbits \
+  --undefok=use_blob_cache,use_shared_block_and_blob_cache,blob_cache_size,blob_cache_numshardbits \
 "
 
 # TODO: