diff --git a/external/CMakeLists.txt b/external/CMakeLists.txt
index 5cc506753..5466117df 100644
--- a/external/CMakeLists.txt
+++ b/external/CMakeLists.txt
@@ -14,6 +14,10 @@ if(${CMAKE_VERSION} VERSION_GREATER_EQUAL "3.24.0")
   set(find_pkg_args "FIND_PACKAGE_ARGS" "${fmt_min_version}")
 endif()
 
+set(FMT_SYSTEM_HEADERS
+    ON
+    CACHE INTERNAL "")
+
 FetchContent_Declare(
   fmt
   GIT_REPOSITORY https://github.com/fmtlib/fmt.git