diff --git a/build.sh b/build.sh
index 0d90ed1..f44e849 100755
--- a/build.sh
+++ b/build.sh
@@ -1,12 +1,13 @@
 #!/bin/bash -e
 
-export IMG_DATE="$(date +%Y-%m-%d)"
 export BASE_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 export SCRIPT_DIR="$BASE_DIR/scripts"
 export FUNCTIONS_DIR="$BASE_DIR/functions"
-export WORK_DIR="$BASE_DIR/work/$IMG_DATE-$IMG_NAME"
 export DEPLOY_DIR="$BASE_DIR/deploy"
 
+export IMG_DATE
+export WORK_DIR
+
 export CLEAN
 export IMG_NAME
 export HOSTNAME
@@ -61,6 +62,9 @@ main() {
     exit 1
   fi
 
+  IMG_DATE="$(date +%Y-%m-%d)"
+  WORK_DIR="$BASE_DIR/work/$IMG_DATE-$IMG_NAME"
+
   mkdir -p "$WORK_DIR"
   run_base
 }