diff --git a/falcon/util/uri.py b/falcon/util/uri.py
index f614e1b23..c7cf2e055 100644
--- a/falcon/util/uri.py
+++ b/falcon/util/uri.py
@@ -49,9 +49,9 @@
 _HEX_DIGITS = '0123456789ABCDEFabcdef'
 
 # This map construction is based on urllib's implementation
-_HEX_TO_BYTE = dict(((a + b).encode(), bytes([int(a + b, 16)]))
-                    for a in _HEX_DIGITS
-                    for b in _HEX_DIGITS)
+_HEX_TO_BYTE = {(a + b).encode(): bytes([int(a + b, 16)])
+                for a in _HEX_DIGITS
+                for b in _HEX_DIGITS}
 
 _PYPY = platform.python_implementation() == 'PyPy'