diff --git a/install.sh b/install.sh
index 0250e7b..3bafd52 100644
--- a/install.sh
+++ b/install.sh
@@ -1,5 +1,9 @@
 #!/bin/bash
 
+if [ -z "$PREFIX" ]; then
+  $PREFIX=""
+fi
+
 ###############################
 #                             #
 #         http_get            #