diff --git a/pyopencl/cffi_cl.py b/pyopencl/cffi_cl.py
index 456813b2f56fd9b70d3e22f3a8ae33d9dfe9264c..560fd7562d93c381969d716e973c2c3644bbebcc 100644
--- a/pyopencl/cffi_cl.py
+++ b/pyopencl/cffi_cl.py
@@ -251,6 +251,8 @@ def _constant_callback(type_, name, value):
 _lib.populate_constants(_constant_callback)
 
 for type_, d in _constants.iteritems():
+    if sys.version_info >= (3,):
+        type_ = type_.decode()
     locals()[type_] = type(type_, (_NoInit,), d)
 
 # }}}