diff --git a/.gitmodules b/.gitmodules
index 062cc71..248fb42 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -2,3 +2,6 @@
 	path = extern/pybind11
 	url = ../../pybind/pybind11
 	branch = stable
+[submodule "extern/json"]
+	path = extern/json
+	url = https://github.com/nlohmann/json
diff --git a/extern/json b/extern/json
new file mode 160000
index 0000000..7efe875
--- /dev/null
+++ b/extern/json
@@ -0,0 +1 @@
+Subproject commit 7efe875495a3ed7d805ddbb01af0c7725f50c88b