diff --git a/ci/build.sh b/ci/build.sh
index 1f84af9..47e20d8 100755
--- a/ci/build.sh
+++ b/ci/build.sh
@@ -20,6 +20,11 @@
     export CXX=clang++
     export LD=clang
     export CXXFLAGS="-stdlib=libc++"
+    # spdlog passes std::string instances, and it's built against GCC's libstdc++ on the CI
+    sed -i \
+        -e 's/spdlog::spdlog/spdlog::spdlog_header_only/' \
+        -e '/find_package(spdlog/ a add_definitions(-DFMT_HEADER_ONLY)' \
+        ${ZUUL_PROJECT_SRC_DIR}/CMakeLists.txt
 fi
 
 if [[ $ZUUL_JOB_NAME =~ .*-ubsan ]]; then