diff --git a/git-ftp.py b/git-ftp.py
index f4453ee..2548b84 100755
--- a/git-ftp.py
+++ b/git-ftp.py
@@ -145,7 +145,15 @@ def main():
             raise FtpSslNotSupported("Python is too old for FTP SSL. Try using Python 2.7 or later.")
     else:
         ftp = ftplib.FTP(options.ftp.hostname, options.ftp.username, options.ftp.password)
-    ftp.cwd(base)
+
+    # Make the base directory an absolute path - it is required for the subsequent steps
+    if base[0] != '/':
+        base = os.path.join(ftp.pwd(), base)
+
+    try:
+        ftp.cwd(base)
+    except ftplib.error_perm:
+        raise ValueError("FTP base directory '%s' does not exist on this server (note: the server session starts at '%s')" % (base, ftp.pwd()))
 
     # Check revision
     hash = options.revision