diff --git a/ProcessLib/SteadyStateDiffusion/CMakeLists.txt b/ProcessLib/SteadyStateDiffusion/CMakeLists.txt
index 8f18f82215a21c166e58f736342e14e220a2822b..ba3bfc7283fb77892fe9bce68075d509841dea46 100644
--- a/ProcessLib/SteadyStateDiffusion/CMakeLists.txt
+++ b/ProcessLib/SteadyStateDiffusion/CMakeLists.txt
@@ -6,4 +6,6 @@ target_link_libraries(
     SteadyStateDiffusion PUBLIC ProcessLib PRIVATE ParameterLib
 )
 
-include(Tests.cmake)
+if(OGS_BUILD_TESTING)
+    include(Tests.cmake)
+endif()