diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..76b1409
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,6 @@
+[submodule "submodules/extism"]
+	path = submodules/extism
+	url = https://github.com/extism/extism.git
+[submodule "submodules/jsoncpp"]
+	path = submodules/jsoncpp
+	url = https://github.com/open-source-parsers/jsoncpp
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 26e9fa9..c797d09 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -9,12 +9,22 @@ link_directories(/opt/homebrew/lib)
 project(extism-cpp VERSION 1.0.0 DESCRIPTION "C++ bindings for libextism")
 set(extism-cpp-srcs src/manifest.cpp src/current_plugin.cpp src/plugin.cpp src/function.cpp src/extism.cpp)
 
+option(EXTISM_CPP_BUILD_IN_TREE "Set to ON to build with submodule deps" OFF)
+if(EXTISM_CPP_BUILD_IN_TREE)
+    add_subdirectory(submodules/extism/libextism)
+    add_subdirectory(submodules/jsoncpp)
+endif()
+
 # SHARED
 add_library(extism-cpp SHARED ${extism-cpp-srcs})
 set_target_properties(extism-cpp PROPERTIES VERSION ${PROJECT_VERSION})
 set_target_properties(extism-cpp PROPERTIES PUBLIC_HEADER src/extism.hpp)
 target_include_directories(extism-cpp PUBLIC src)
-target_link_libraries(extism-cpp PUBLIC extism jsoncpp)
+if(EXTISM_CPP_BUILD_IN_TREE)
+    target_link_libraries(extism-cpp PUBLIC extism-shared jsoncpp)
+else()
+    target_link_libraries(extism-cpp PUBLIC extism jsoncpp)
+endif()
 set_target_properties(extism-cpp
   PROPERTIES NO_SONAME 1
 )
@@ -26,7 +36,11 @@ set_target_properties(extism-cpp-static PROPERTIES OUTPUT_NAME extism-cpp)
 set_target_properties(extism-cpp-static PROPERTIES VERSION ${PROJECT_VERSION})
 set_target_properties(extism-cpp-static PROPERTIES PUBLIC_HEADER src/extism.hpp)
 target_include_directories(extism-cpp-static PUBLIC src)
-target_link_libraries(extism-cpp-static PUBLIC libextism.a jsoncpp)
+if(EXTISM_CPP_BUILD_IN_TREE)
+    target_link_libraries(extism-cpp-static PUBLIC extism-static jsoncpp_static)
+else()
+    target_link_libraries(extism-cpp-static PUBLIC libextism.a jsoncpp)
+endif()
 configure_file(extism-cpp-static.pc.in extism-cpp-static.pc @ONLY)
 
 include(GNUInstallDirs)
diff --git a/README.md b/README.md
index 7bc491f..d2bbdec 100644
--- a/README.md
+++ b/README.md
@@ -63,3 +63,13 @@ $ pkg-config --libs extism-cpp
 ```shell
 $ pkg-config --static --libs extism-cpp-static
 ```
+
+## In-Tree builds
+
+If you wish, instead of using installed deps, you can do an in-tree build:
+
+```shell
+git clone --recurse-submodules -j4 https://github.com/extism/cpp-sdk.git
+cd cpp-sdk
+cmake -DEXTISM_CPP_BUILD_IN_TREE=1 -B build && cmake --build build
+```
diff --git a/submodules/extism b/submodules/extism
new file mode 160000
index 0000000..7636c87
--- /dev/null
+++ b/submodules/extism
@@ -0,0 +1 @@
+Subproject commit 7636c87319ba189825302ab24084214a43163b2b
diff --git a/submodules/jsoncpp b/submodules/jsoncpp
new file mode 160000
index 0000000..69098a1
--- /dev/null
+++ b/submodules/jsoncpp
@@ -0,0 +1 @@
+Subproject commit 69098a18b9af0c47549d9a271c054d13ca92b006