diff --git a/scripts/formulas/msdf-atlas-gen.sh b/scripts/formulas/msdf-atlas-gen.sh
index bc6b99d..d0bc9bd 100644
--- a/scripts/formulas/msdf-atlas-gen.sh
+++ b/scripts/formulas/msdf-atlas-gen.sh
@@ -114,6 +114,7 @@ function build() {
     elif [ "$TYPE" == "emscripten" ] ; then
         cd lib/$TYPE
         emcmake cmake \
+            -DCMAKE_CXX_FLAGS="-pthread" \
             -DMSDF_ATLAS_BUILD_STANDALONE=OFF \
             -DMSDF_ATLAS_USE_VCPKG=OFF \
             -DMSDF_ATLAS_USE_SKIA=OFF \