diff --git a/install_lichen.sh b/install_lichen.sh
index 1f0bc34..f51d6b9 100755
--- a/install_lichen.sh
+++ b/install_lichen.sh
@@ -55,7 +55,7 @@ fi
 # compile & install the hash comparison tool
 
 pushd "${lichen_repository_dir}" > /dev/null
-clang++ -I "${lichen_vendor_dir}" -lboost_system -lboost_filesystem -Wall -Wextra -Werror -g -Ofast -flto -funroll-loops -std=c++11 compare_hashes/compare_hashes.cpp compare_hashes/submission.cpp -o "${lichen_installation_dir}/compare_hashes/compare_hashes.out"
+clang++ -I "${lichen_vendor_dir}" -lboost_system -lboost_filesystem -Wall -Wextra -Werror -g -O3 -flto -funroll-loops -std=c++11 compare_hashes/compare_hashes.cpp compare_hashes/submission.cpp -o "${lichen_installation_dir}/compare_hashes/compare_hashes.out"
 if [ "$?" -ne 0 ]; then
     echo -e "ERROR: FAILED TO BUILD HASH COMPARISON TOOL\n"
     exit 1