diff --git a/Tests/RunCMake/find_program/IgnorePrefixPath.cmake b/Tests/RunCMake/find_program/IgnorePrefixPath.cmake
index 5f0dba9d5b..b055af0068 100644
--- a/Tests/RunCMake/find_program/IgnorePrefixPath.cmake
+++ b/Tests/RunCMake/find_program/IgnorePrefixPath.cmake
@@ -5,6 +5,7 @@ function(assert_eq var value)
 endfunction()
 
 set(CMAKE_FIND_USE_SYSTEM_ENVIRONMENT_PATH FALSE)
+set(CMAKE_SYSTEM_PROGRAM_PATH)
 
 set(CMAKE_PREFIX_PATH ${CMAKE_SOURCE_DIR}/Prefix)
 set(_old_CMAKE_SYSTEM_PREFIX_PATH ${CMAKE_SYSTEM_PREFIX_PATH})