diff --git a/cpp/.envrc b/cpp/.envrc
index e62a47d..3506d1c 100644
--- a/cpp/.envrc
+++ b/cpp/.envrc
@@ -1 +1,2 @@
-export CXXFLAGS="-std=c++20 -Wall -Wextra -g"
+export CXXFLAGS="-std=c++20 -Wall -Wextra -g -D_MF_TEST"
+export LDLIBS="-lgtest"