diff --git a/rbutil/rbutilqt/deploy-release.py b/rbutil/rbutilqt/deploy-release.py
index dab0e8a7dc..4b3b91576a 100755
--- a/rbutil/rbutilqt/deploy-release.py
+++ b/rbutil/rbutilqt/deploy-release.py
@@ -42,12 +42,24 @@ import zipfile
 import shutil
 import subprocess
 import getopt
-import which
 import time
 import hashlib
-import pysvn
 import tempfile
 
+# modules that are not part of python itself.
+try:
+    import pysvn
+except ImportError:
+    print "Fatal: This script requires the pysvn package to run."
+    print "       See http://pysvn.tigris.org/."
+    sys.exit(-5)
+try:
+    import which
+except ImportError:
+    print "Fatal: This script requires the which package to run."
+    print "       See http://code.google.com/p/which/."
+    sys.exit(-5)
+
 # == Global stuff ==
 # Windows nees some special treatment. Differentiate between program name
 # and executable filename.