diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 1096dd3..ed46443 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -1,17 +1,20 @@
-include(FetchContent)
+find_library(DOCTEST_LIB doctest)
 
-FetchContent_Declare(
+if(NOT DOCTEST_LIB)
+  include(FetchContent)
+
+  FetchContent_Declare(
     DocTest
     GIT_REPOSITORY https://github.com/doctest/doctest.git
-    GIT_TAG v2.4.9
-)
+    GIT_TAG v2.4.9)
 
-FetchContent_MakeAvailable(DocTest)
+  FetchContent_MakeAvailable(DocTest)
+endif()
 
 add_executable(testTug setup.cpp testBoundaryCondition.cpp testDiffusion.cpp)
 target_link_libraries(testTug doctest tug)
 
-add_custom_target(check
-    COMMAND $<TARGET_FILE:testTug>
-    DEPENDS testTug
-)
+add_custom_target(
+  check
+  COMMAND $<TARGET_FILE:testTug>
+  DEPENDS testTug)