diff --git a/Tests/RunCMake/FindBoost/RunCMakeTest.cmake b/Tests/RunCMake/FindBoost/RunCMakeTest.cmake
index 5d0577b2d3..eef350c6c8 100644
--- a/Tests/RunCMake/FindBoost/RunCMakeTest.cmake
+++ b/Tests/RunCMake/FindBoost/RunCMakeTest.cmake
@@ -1,4 +1,5 @@
 include(RunCMake)
+unset(ENV{Boost_ROOT})
 
 run_cmake(CMakePackage)
 run_cmake(NoCXX)