diff --git a/vdirsyncer/utils/compat.py b/vdirsyncer/utils/compat.py
index 2d33065..840bc52 100644
--- a/vdirsyncer/utils/compat.py
+++ b/vdirsyncer/utils/compat.py
@@ -4,6 +4,11 @@ import sys
 
 PY2 = sys.version_info[0] == 2
 
+if sys.version_info < (3, 3) and sys.version_info[:2] != (2, 7):
+    raise RuntimeError(
+        'vdirsyncer only works on Python versions 2.7.x and 3.3+'
+    )
+
 
 if PY2:  # pragma: no cover
     import urlparse