diff --git a/apps/emqx/rebar.config b/apps/emqx/rebar.config
index cbaae0b39..3822078b7 100644
--- a/apps/emqx/rebar.config
+++ b/apps/emqx/rebar.config
@@ -30,7 +30,7 @@
     {esockd, {git, "https://github.com/emqx/esockd", {tag, "5.11.1"}}},
     {ekka, {git, "https://github.com/emqx/ekka", {tag, "0.19.0"}}},
     {gen_rpc, {git, "https://github.com/emqx/gen_rpc", {tag, "3.3.1"}}},
-    {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.42.0"}}},
+    {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.42.1"}}},
     {emqx_http_lib, {git, "https://github.com/emqx/emqx_http_lib.git", {tag, "0.5.3"}}},
     {pbkdf2, {git, "https://github.com/emqx/erlang-pbkdf2.git", {tag, "2.0.4"}}},
     {recon, {git, "https://github.com/ferd/recon", {tag, "2.5.1"}}},
diff --git a/changes/ce/feat-12700.en.md b/changes/ce/feat-12700.en.md
new file mode 100644
index 000000000..5b1799c75
--- /dev/null
+++ b/changes/ce/feat-12700.en.md
@@ -0,0 +1,9 @@
+Support "b" and "B" unit in bytesize hocon fields.
+
+For example, all three fields below will have the value of 1024 bytes:
+
+```
+bytesize_field = "1024b"
+bytesize_field2 = "1024B"
+bytesize_field2 = 1024
+```
diff --git a/mix.exs b/mix.exs
index 668459e24..dfd34be8a 100644
--- a/mix.exs
+++ b/mix.exs
@@ -72,7 +72,7 @@ defmodule EMQXUmbrella.MixProject do
       # in conflict by emqtt and hocon
       {:getopt, "1.0.2", override: true},
       {:snabbkaffe, github: "kafka4beam/snabbkaffe", tag: "1.0.8", override: true},
-      {:hocon, github: "emqx/hocon", tag: "0.42.0", override: true},
+      {:hocon, github: "emqx/hocon", tag: "0.42.1", override: true},
       {:emqx_http_lib, github: "emqx/emqx_http_lib", tag: "0.5.3", override: true},
       {:esasl, github: "emqx/esasl", tag: "0.2.0"},
       {:jose, github: "potatosalad/erlang-jose", tag: "1.11.2"},
diff --git a/rebar.config b/rebar.config
index 5e6bafb15..e6b1ee70e 100644
--- a/rebar.config
+++ b/rebar.config
@@ -97,7 +97,7 @@
     {system_monitor, {git, "https://github.com/ieQu1/system_monitor", {tag, "3.0.3"}}},
     {getopt, "1.0.2"},
     {snabbkaffe, {git, "https://github.com/kafka4beam/snabbkaffe.git", {tag, "1.0.8"}}},
-    {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.42.0"}}},
+    {hocon, {git, "https://github.com/emqx/hocon.git", {tag, "0.42.1"}}},
     {emqx_http_lib, {git, "https://github.com/emqx/emqx_http_lib.git", {tag, "0.5.3"}}},
     {esasl, {git, "https://github.com/emqx/esasl", {tag, "0.2.0"}}},
     {jose, {git, "https://github.com/potatosalad/erlang-jose", {tag, "1.11.2"}}},