diff --git a/configure.sh b/configure.sh
index b2a8e3cff..413652ddc 100755
--- a/configure.sh
+++ b/configure.sh
@@ -5,9 +5,9 @@
 
 echo "Configuring the repository for development..."
 
-SKIP_MAP_DOWNLOAD=$SKIP_MAP_DOWNLOAD
-SKIP_GENERATE_SYMBOLS=$SKIP_GENERATE_SYMBOLS
-SKIP_GENERATE_DRULES=$SKIP_GENERATE_DRULES
+SKIP_MAP_DOWNLOAD="${SKIP_MAP_DOWNLOAD:-}"
+SKIP_GENERATE_SYMBOLS="${SKIP_GENERATE_SYMBOLS:-}"
+SKIP_GENERATE_DRULES="${SKIP_GENERATE_DRULES:-}"
 
 DRULES_NOT_GENERATED=
 SYMBOLS_NOT_GENERATED=