diff --git a/external/external_build.cmake b/external/external_build.cmake
index 997cc4d..54a9a27 100644
--- a/external/external_build.cmake
+++ b/external/external_build.cmake
@@ -383,6 +383,7 @@ IF (INTERNAL_EIGEN)
      CMAKE_ARGS -DCMAKE_INSTALL_PREFIX=${EXT_INSTALL}
        -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
        -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
+       -DCMAKE_POLICY_VERSION_MINIMUM=3.5
   )
   SET(EIGEN3_INCLUDEDIR ${EXT_INSTALL}/include/eigen3)