diff --git a/stdlib/2and3/cmath.pyi b/stdlib/2and3/cmath.pyi
index bcfc6f605..4b15f0b78 100644
--- a/stdlib/2and3/cmath.pyi
+++ b/stdlib/2and3/cmath.pyi
@@ -1,12 +1,18 @@
 """Stub file for the 'cmath' module."""
 
 import sys
-from typing import Union, Tuple
+from typing import SupportsComplex, SupportsFloat, Tuple, Union
 
 e: float
 pi: float
+if sys.version_info >= (3, 6):
+    inf: float
+    infj: complex
+    nan: float
+    nanj: complex
+    tau: float
 
-_C = Union[float, complex]
+_C = Union[SupportsFloat, SupportsComplex]
 
 def acos(x: _C) -> complex: ...
 def acosh(x: _C) -> complex: ...
@@ -17,6 +23,8 @@ def atanh(x: _C) -> complex: ...
 def cos(x: _C) -> complex: ...
 def cosh(x: _C) -> complex: ...
 def exp(x: _C) -> complex: ...
+if sys.version_info >= (3, 5):
+    def isclose(a: _C, b: _C, *, rel_tol: SupportsFloat = ..., abs_tol: SupportsFloat = ...) -> bool: ...
 def isinf(z: _C) -> bool: ...
 def isnan(z: _C) -> bool: ...
 def log(x: _C, base: _C = ...) -> complex: ...