diff --git a/cm_library_c_binding/CMakeLists.txt b/cm_library_c_binding/CMakeLists.txt
index 9a96f6dd..c61c3294 100644
--- a/cm_library_c_binding/CMakeLists.txt
+++ b/cm_library_c_binding/CMakeLists.txt
@@ -35,5 +35,4 @@ add_custom_command(
 )
 
 add_custom_target(cffi-c-binding ALL DEPENDS ${CFFI_C_CODE_DIR}/${CFFI_C_CODE})
-target_include_directories(cffi-c-binding PUBLIC ${VENDORED_HEADERS_DIR})
 add_dependencies(cffi-c-binding headers-for-cffi)
diff --git a/cm_python_module/CMakeLists.txt b/cm_python_module/CMakeLists.txt
index 2588a2ac..c73cc637 100644
--- a/cm_python_module/CMakeLists.txt
+++ b/cm_python_module/CMakeLists.txt
@@ -23,8 +23,8 @@ if (PROJECT_IGNORE_SYSTEM_LIB OR NOT VENDORED_AS_SYSTEM_LIB_FOUND)
     # https://docs.python.org/3/c-api/stable.html#limited-c-api
     target_link_libraries(${CFFI_OUTPUT_LIBRARY} PRIVATE ${CFFI_INPUT_LIBRARY})
 elseif(VENDORED_AS_SYSTEM_LIB_FOUND)
-    message(STATUS "Vendored system library found: ${VENDORED_AS_SYSTEM_LIB_LINK_LIBRARIES}")
-    target_include_directories(${CFFI_OUTPUT_LIBRARY} PRIVATE ${VENDORED_AS_SYSTEM_LIB_LIBRARIES})
+    message(STATUS "Vendored system library found: ${VENDORED_AS_SYSTEM_LIB_LIBRARIES}")
+    target_include_directories(${CFFI_OUTPUT_LIBRARY} PRIVATE ${VENDORED_AS_SYSTEM_LIB_INCLUDE_DIRS})
     add_dependencies(${CFFI_OUTPUT_LIBRARY} cffi-c-binding)
     # On windows, using the LDFLAGS field creates /libpath... secp256k1.lib (correct), but at a later stage
     # /libpath is converted to \libpath and fails to be interpreted as a flag by the linker