diff --git a/.gitmodules b/.gitmodules
index 4ee89fc4..448dcc04 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,3 +4,6 @@
 [submodule "extern/asio"]
 	path = extern/asio
 	url = https://github.com/chriskohlhoff/asio
+[submodule "extern/PicoSHA2"]
+	path = extern/PicoSHA2
+	url = https://github.com/okdshin/PicoSHA2
diff --git a/extern/PicoSHA2 b/extern/PicoSHA2
new file mode 160000
index 00000000..599843c3
--- /dev/null
+++ b/extern/PicoSHA2
@@ -0,0 +1 @@
+Subproject commit 599843c396681cc1ee54bde86848cc0b032fff93