diff --git a/Misc/NEWS b/Misc/NEWS
index 794363ee142..f3e0db97f8f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -99,6 +99,9 @@ Tests
 Build
 -----
 
+- Issue #15923: fix a mistake in asdl_c.py that resulted in a TypeError after
+  2801bf875a24 (see #15801).
+
 - Issue #15819: Make sure we can build Python out-of-tree from a readonly
   source directory.  (Somewhat related to Issue #9860.)
 
diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
index 698afacf890..57483609fd9 100755
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -1064,7 +1064,7 @@ def simpleSum(self, sum, name):
             self.emit("case %s:" % t.name, 2)
             self.emit("Py_INCREF(%s_singleton);" % t.name, 3)
             self.emit("return %s_singleton;" % t.name, 3)
-        self.emit("default:" % name, 2)
+        self.emit("default:", 2)
         self.emit('/* should never happen, but just in case ... */', 3)
         code = "PyErr_Format(PyExc_SystemError, \"unknown %s found\");" % name
         self.emit(code, 3, reflow=False)