diff --git a/c_mpos/micropython.cmake b/c_mpos/micropython.cmake
new file mode 100644
index 00000000..32556124
--- /dev/null
+++ b/c_mpos/micropython.cmake
@@ -0,0 +1,26 @@
+# Seems this must be passed as:
+# USER_C_MODULE=/home/user/sources/PiggyOS/c_mpos/micropython.cmake
+# ...to make.py when building for esp32 to ensure it gets compiled.
+
+add_library(usermod_c_mpos INTERFACE)
+
+set(MPOS_C_INCLUDES)
+
+set(MPOS_C_SOURCES
+    ${CMAKE_CURRENT_LIST_DIR}/src/hello_world.c
+    ${CMAKE_CURRENT_LIST_DIR}/src/quirc_decode.c
+    ${CMAKE_CURRENT_LIST_DIR}/quirc/lib/identify.c
+    ${CMAKE_CURRENT_LIST_DIR}/quirc/lib/version_db.c
+    ${CMAKE_CURRENT_LIST_DIR}/quirc/lib/decode.c
+    ${CMAKE_CURRENT_LIST_DIR}/quirc/lib/quirc.c
+)
+
+# Add our source files to the lib
+target_sources(usermod_c_mpos INTERFACE ${MPOS_C_SOURCES})
+
+# Add include directories.
+target_include_directories(usermod_c_mpos INTERFACE ${MPOS_C_INCLUDES})
+
+# Link our INTERFACE library to the usermod target.
+target_link_libraries(usermod INTERFACE usermod_c_mpos)
+