2 files changed, 15 insertions, 1 deletions
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index cf4b0e1..8ebe970 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -1784,6 +1784,18 @@ raise_exception(PyObject *self, PyObject *args)
 }
 
 static PyObject *
+set_errno(PyObject *self, PyObject *args)
+{
+    int new_errno;
+
+    if (!PyArg_ParseTuple(args, "i:set_errno", &new_errno))
+        return NULL;
+
+    errno = new_errno;
+    Py_RETURN_NONE;
+}
+
+static PyObject *
 test_set_exc_info(PyObject *self, PyObject *args)
 {
     PyObject *orig_exc;
@@ -3208,6 +3220,7 @@ pymarshal_read_object_from_file(PyObject* self, PyObject *args)
 static PyMethodDef TestMethods[] = {
     {"raise_exception",         raise_exception,                 METH_VARARGS},
     {"raise_memoryerror",   (PyCFunction)raise_memoryerror,  METH_NOARGS},
+    {"set_errno",               set_errno,                       METH_VARARGS},
     {"test_config",             (PyCFunction)test_config,        METH_NOARGS},
     {"test_sizeof_c_types",     (PyCFunction)test_sizeof_c_types, METH_NOARGS},
     {"test_datetime_capi",  test_datetime_capi,              METH_NOARGS},
diff --git a/Modules/cmathmodule.c b/Modules/cmathmodule.c
index eb2853c..b341c34 100644
--- a/Modules/cmathmodule.c
+++ b/Modules/cmathmodule.c
@@ -941,9 +941,10 @@ cmath_polar(PyObject *self, PyObject *args)
     double r, phi;
     if (!PyArg_ParseTuple(args, "D:polar", &z))
         return NULL;
+    errno = 0;
     PyFPE_START_PROTECT("polar function", return 0)
     phi = c_atan2(z); /* should not cause any exception */
-    r = c_abs(z); /* sets errno to ERANGE on overflow;  otherwise 0 */
+    r = c_abs(z); /* sets errno to ERANGE on overflow */
     PyFPE_END_PROTECT(r)
     if (errno != 0)
         return math_error();