diff --git a/CMakeLists.txt b/CMakeLists.txt
index ba8e8ea..bacac20 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -8,6 +8,7 @@ if (NOT DEFINED OPTCON_LOCAL_BUILD)
         fmt
         GIT_REPOSITORY https://github.com/fmtlib/fmt
         GIT_TAG 123913715afeb8a437e6388b4473fcc4753e1c9a # 11.1.4
+        SYSTEM
     )
 
     FetchContent_MakeAvailable(fmt)