diff --git a/README.md b/README.md
index 7ce6e00..43cd5c1 100644
--- a/README.md
+++ b/README.md
@@ -90,7 +90,7 @@ python rwkv/quantize.py ~/Downloads/rwkv.cpp-169M.bin ~/Downloads/rwkv.cpp-169M-
 
 Formats available:
 
-- `4`: `Q4_1_O`, OK quality, fast (comparable to `FP16`).
+- `4`: `Q4_1_O`, OK quality, moderately fast (20% slower than `FP16`).
 - `3`: `Q4_1`, worst quality, fast (comparable to `FP16`).
 - `2`: `Q4_0`, poor quality, very fast.
 
diff --git a/ggml b/ggml
index fbf4d60..538e516 160000
--- a/ggml
+++ b/ggml
@@ -1 +1 @@
-Subproject commit fbf4d6052fd2df028169a5609a4f45fbbdf6eece
+Subproject commit 538e516aced0aae5b22cbe7e691169e6957df753