diff --git a/thermion_dart/native/src/c_api/TEngine.cpp b/thermion_dart/native/src/c_api/TEngine.cpp
index 93532153..60b9bf5b 100644
--- a/thermion_dart/native/src/c_api/TEngine.cpp
+++ b/thermion_dart/native/src/c_api/TEngine.cpp
@@ -40,10 +40,10 @@ namespace thermion
         using namespace filament;
 #endif
 
-        uint64_t TSWAP_CHAIN_CONFIG_TRANSPARENT = filament::backend::SWAP_CHAIN_CONFIG_TRANSPARENT;
-        uint64_t TSWAP_CHAIN_CONFIG_READABLE = filament::backend::SWAP_CHAIN_CONFIG_READABLE;
-        uint64_t TSWAP_CHAIN_CONFIG_APPLE_CVPIXELBUFFER = filament::backend::SWAP_CHAIN_CONFIG_APPLE_CVPIXELBUFFER;
-        uint64_t TSWAP_CHAIN_CONFIG_HAS_STENCIL_BUFFER = filament::backend::SWAP_CHAIN_CONFIG_HAS_STENCIL_BUFFER;
+        EMSCRIPTEN_KEEPALIVE uint64_t TSWAP_CHAIN_CONFIG_TRANSPARENT = filament::backend::SWAP_CHAIN_CONFIG_TRANSPARENT;
+        EMSCRIPTEN_KEEPALIVE uint64_t TSWAP_CHAIN_CONFIG_READABLE = filament::backend::SWAP_CHAIN_CONFIG_READABLE;
+        EMSCRIPTEN_KEEPALIVE uint64_t TSWAP_CHAIN_CONFIG_APPLE_CVPIXELBUFFER = filament::backend::SWAP_CHAIN_CONFIG_APPLE_CVPIXELBUFFER;
+        EMSCRIPTEN_KEEPALIVE uint64_t TSWAP_CHAIN_CONFIG_HAS_STENCIL_BUFFER = filament::backend::SWAP_CHAIN_CONFIG_HAS_STENCIL_BUFFER;
 
         EMSCRIPTEN_KEEPALIVE TEngine *Engine_create(
             TBackend backend,