diff --git a/common.py b/common.py
index b33e171..eecf2a7 100644
--- a/common.py
+++ b/common.py
@@ -277,7 +277,8 @@ def run_cmd(
     env = os.environ.copy()
     env.update(extra_env)
     for key in delete_env:
-        del env[key]
+        if key in env:
+            del env[key]
     if show_cmd:
         print_cmd(cmd, cmd_file, extra_env=extra_env)
     # Otherwise Ctrl + C gives:
diff --git a/configure b/configure
index b8c24af..b8c12fd 100755
--- a/configure
+++ b/configure
@@ -44,6 +44,7 @@ cpio \
 expect \
 git \
 moreutils \
+rsync \
 tmux \
 unzip \
 vinagre \