diff --git a/ci/run.sh b/ci/run.sh
index 30427d27acc96..303a4afacea0a 100755
--- a/ci/run.sh
+++ b/ci/run.sh
@@ -113,6 +113,8 @@ else
       # Rust uses -g4 by default what causes link issues.
       # This should disable the -g4 option.
       export RUSTFLAGS="-Cdebuginfo=0"
+      export EMCC_FLAGS="-s USE_PTHREADS=1 --shared-memory"
+      export EMCC_CFLAGS="-s USE_PTHREADS=1 --shared-memory"
   fi
   cargo test --no-default-features --manifest-path libc-test/Cargo.toml \
     --target "${TARGET}" ${LIBC_CI_ZBUILD_STD+"-Zbuild-std"}