diff --git a/modules/CMakeLists.txt b/modules/CMakeLists.txt
index 8952c96..d4dc54f 100644
--- a/modules/CMakeLists.txt
+++ b/modules/CMakeLists.txt
@@ -34,6 +34,10 @@ add_library(clock ${lib_type} clock.c)
 target_link_libraries(clock module-sdk)
 
 pkg_check_modules(JSON REQUIRED json-c)
+find_file(I3_IPC_H i3/ipc.h)
+if (NOT I3_IPC_H)
+  message(FATAL_ERROR "cannot find header file: i3/ipc.h")
+endif ()
 add_library(i3 ${lib_type} i3.c)
 target_compile_options(i3 PRIVATE ${JSON_CFLAGS_OTHER})
 target_include_directories(i3 PRIVATE ${JSON_INCLUDE_DIRS})