diff --git a/reg_tests/CMakeLists.txt b/reg_tests/CMakeLists.txt
index 81271ef48..100a3ce65 100644
--- a/reg_tests/CMakeLists.txt
+++ b/reg_tests/CMakeLists.txt
@@ -29,7 +29,7 @@ else(NOT ${TEST_TOLERANCE} STREQUAL "")
     endif()
   elseif(${CMAKE_SYSTEM_NAME} MATCHES "Linux")
     if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
-      set(TOLERANCE 0.0000001)
+      set(TOLERANCE 0.000001)
     elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
       set(TOLERANCE 0.000000000000001)
     elseif ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Intel")