diff --git a/module-template/CMakeLists.txt b/module-template/CMakeLists.txt
index 2757a8d96d..3b00450722 100644
--- a/module-template/CMakeLists.txt
+++ b/module-template/CMakeLists.txt
@@ -130,8 +130,22 @@ if(NOT RECOMPCORE_MODULE_OPT_LEVEL MATCHES "^[0-3]$")
 endif()
 if(RECOMPCORE_MODULE_ENABLE_IPO AND CMAKE_C_COMPILER_ID MATCHES "Clang")
   include(CheckIPOSupported)
+  # moderngekko-port configures with CMAKE_NINJA_FORCE_RESPONSE_FILE=1, which the
+  # module needs: it links thousands of chunk objects and the command line does
+  # not fit in ARG_MAX. But check_ipo_supported's try-compile inherits the
+  # environment, and its static-library step then runs `ar qc libfoo.a @foo.rsp`
+  # -- Apple's /usr/bin/ar has no @file support, so the check fails with
+  # "ar: @CMakeFiles/foo.rsp: No such file or directory" and IPO is silently
+  # disabled. The manifest still records -flto=thin. Every module built this way
+  # had NO cross-translation-unit inlining. Scope the variable off for the check
+  # only, then restore it before the generator reads it.
+  set(_module_forced_rsp "$ENV{CMAKE_NINJA_FORCE_RESPONSE_FILE}")
+  unset(ENV{CMAKE_NINJA_FORCE_RESPONSE_FILE})
   check_ipo_supported(RESULT RECOMPCORE_MODULE_IPO_SUPPORTED
                       OUTPUT RECOMPCORE_MODULE_IPO_ERROR LANGUAGES C)
+  if(_module_forced_rsp)
+    set(ENV{CMAKE_NINJA_FORCE_RESPONSE_FILE} "${_module_forced_rsp}")
+  endif()
   if(RECOMPCORE_MODULE_IPO_SUPPORTED)
     set_property(TARGET ${MODULE_NAME} PROPERTY INTERPROCEDURAL_OPTIMIZATION TRUE)
   else()