diff --git a/.gitmodules b/.gitmodules
index d013618..707d577 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -14,3 +14,6 @@
 [submodule "Keishiki/ext/plf_colony"]
 	path = Keishiki/ext/plf_colony
 	url = https://github.com/mattreecebentley/plf_colony.git
+[submodule "Keishiki/ext/fmt"]
+	path = Keishiki/ext/fmt
+	url = https://github.com/fmtlib/fmt.git
diff --git a/Keishiki/ext/fmt b/Keishiki/ext/fmt
new file mode 160000
index 0000000..bbf44cc
--- /dev/null
+++ b/Keishiki/ext/fmt
@@ -0,0 +1 @@
+Subproject commit bbf44cc000531dc7737d5321ccfa9f2f11b20127