diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 46fcf1e9..4679fe1d 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -89,6 +89,9 @@ if (CMAKE_CXX_COMPILER_ID STREQUAL AppleClang AND CMAKE_VERSION VERSION_GREATER_
     elseif(TARGET SPIRV-Tools-shared)
         set_target_properties(SPIRV-Tools-shared PROPERTIES SYSTEM OFF)
     endif()
+    if(TARGET SPIRV-Tools-opt)
+        set_target_properties(SPIRV-Tools-opt PROPERTIES SYSTEM OFF)
+    endif()
     if (TARGET glslang::SPIRV)
         set_target_properties(glslang::SPIRV PROPERTIES SYSTEM OFF)
     endif()