diff --git a/packages/react-native-codegen/scripts/oss/build.sh b/packages/react-native-codegen/scripts/oss/build.sh
index 09b62e8092..28fe87693b 100755
--- a/packages/react-native-codegen/scripts/oss/build.sh
+++ b/packages/react-native-codegen/scripts/oss/build.sh
@@ -17,7 +17,7 @@ rm -rf "${CODEGEN_DIR:?}/lib" "${CODEGEN_DIR:?}/node_modules"
 
 YARN_BINARY="${YARN_BINARY:-$(command -v yarn)}"
 
-if [[ "$FBSOURCE_ENV" -eq "1" ]]; then
+if [[ ${FBSOURCE_ENV:-0} -eq 1 ]]; then
   # Custom FB-specific setup
   pushd "$CODEGEN_DIR" >/dev/null