diff --git a/unittest/force-styles/CMakeLists.txt b/unittest/force-styles/CMakeLists.txt
index 5e0b677042..75e95c3bf0 100644
--- a/unittest/force-styles/CMakeLists.txt
+++ b/unittest/force-styles/CMakeLists.txt
@@ -118,7 +118,7 @@ endforeach()
 # tester for timestepping fixes
 add_executable(test_fix_timestep test_fix_timestep.cpp)
 if(NOT BUILD_SHARED_LIBS)
-  target_compile_definitions(test_fix_timestep -DUSING_STATIC_LIBS=1)
+  target_compile_definitions(test_fix_timestep PRIVATE USING_STATIC_LIBS=1)
 endif()
 target_link_libraries(test_fix_timestep PRIVATE lammps style_tests)