diff --git a/cmake/modules/FindArduino.cmake b/cmake/modules/FindArduino.cmake
index 7faadeba15..a8cc4ae63e 100644
--- a/cmake/modules/FindArduino.cmake
+++ b/cmake/modules/FindArduino.cmake
@@ -288,6 +288,7 @@ function(setup_arduino_core VAR_NAME BOARD_ID)
     if(BOARD_CORE AND NOT TARGET ${CORE_LIB_NAME})
         set(BOARD_CORE_PATH ${ARDUINO_CORES_PATH}/${BOARD_CORE})
         find_sources(CORE_SRCS ${BOARD_CORE_PATH})
+		list(REMOVE_ITEM CORE_SRCS "${BOARD_CORE_PATH}/main.cxx")
         add_library(${CORE_LIB_NAME} ${CORE_SRCS})
         set(${VAR_NAME} ${CORE_LIB_NAME} PARENT_SCOPE)
     endif()