Fixing a bug in install_as_script, from https://github.com/creationix/nvm/commit/516e553093604ac8a0daa4ad7fab2388cc5c88bf
diff --git a/install.sh b/install.sh
index 15de6bf..5296e47 100755
--- a/install.sh
+++ b/install.sh
@@ -82,8 +82,8 @@
   else
     echo "=> Downloading nvm as script to '$NVM_DIR'"
   fi
-  nvm_download -s "$_source" -o "$NVM_DIR/nvm.sh" || {
-    echo >&2 "Failed to download '$_source'.."
+  nvm_download -s "$NVM_SOURCE" -o "$NVM_DIR/nvm.sh" || {
+    echo >&2 "Failed to download '$NVM_SOURCE'.."
     return 1
   }
 }