diff --git a/install.sh b/install.sh
index c8959d43..d8dc188c 100644
--- a/install.sh
+++ b/install.sh
@@ -13,7 +13,7 @@ echo "***********************************************"
 # Check available capacity
 dir_avail() {
 	df -h >/dev/null 2>&1 && h="$2"
-    df -P $h "${1:-.}" 2>/dev/null | awk 'NR==2 {print $(NF-2)}'
+    df -P $h "${1:-.}" 2>/dev/null | awk 'NR==2 {print $4}'
 }
 
 ckcmd() { #检查命令