diff --git a/code/CMakeLists.txt b/code/CMakeLists.txt
index e45bf8a2a..1af9407d2 100644
--- a/code/CMakeLists.txt
+++ b/code/CMakeLists.txt
@@ -1172,7 +1172,7 @@ ELSE()
 ENDIF()
 
 # adds C_FLAGS required to compile zip.c on old GCC 4.x compiler
-TARGET_COMPILE_FEATURES(assimp PUBLIC c_std_99)
+TARGET_COMPILE_FEATURES(assimp PRIVATE c_std_99)
 
 TARGET_INCLUDE_DIRECTORIES ( assimp PUBLIC
   $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../include>