diff --git a/cMake/FreeCAD_Helpers/SetupEigen.cmake b/cMake/FreeCAD_Helpers/SetupEigen.cmake
index 48ae286728..492519a9d9 100644
--- a/cMake/FreeCAD_Helpers/SetupEigen.cmake
+++ b/cMake/FreeCAD_Helpers/SetupEigen.cmake
@@ -11,14 +11,14 @@ macro(SetupEigen)
                 "=================\n")
     endif(NOT EIGEN3_FOUND)
 
-    if (${EIGEN3_VERSION} VERSION_LESS "3.3.1")
+    if (EIGEN3_FOUND AND ${EIGEN3_VERSION} VERSION_LESS "3.3.1")
         message(WARNING "Disable module flatmesh because it requires "
                         "minimum Eigen3 version 3.3.1 but version ${EIGEN3_VERSION} was found")
         set (BUILD_FLAT_MESH OFF)
     endif()
 
     # Older versions raise the warning -Wdeprecated-copy with clang10/gcc10
-    if (${EIGEN3_VERSION} VERSION_LESS "3.3.8")
+    if (EIGEN3_FOUND AND ${EIGEN3_VERSION} VERSION_LESS "3.3.8")
         unset(_flag_found CACHE)
         check_cxx_compiler_flag("-Wno-deprecated-copy" _flag_found)
         if (_flag_found)