diff --git a/Misc/NEWS b/Misc/NEWS
index 031e9de1c1d..087c18b7f76 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -40,6 +40,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #11973: Fix a problem in kevent. The flags and fflags fields are now
+  properly handled as unsigned.
+
 - Issue #18807: ``pyvenv`` now takes a --copies argument allowing copies
   instead of symlinks even where symlinks are available and the default.
 
diff --git a/Modules/selectmodule.c b/Modules/selectmodule.c
index ebd871cf158..5da0d9237eb 100644
--- a/Modules/selectmodule.c
+++ b/Modules/selectmodule.c
@@ -1733,7 +1733,7 @@ kqueue_event_init(kqueue_event_Object *self, PyObject *args, PyObject *kwds)
     PyObject *pfd;
     static char *kwlist[] = {"ident", "filter", "flags", "fflags",
                              "data", "udata", NULL};
-    static char *fmt = "O|hhi" DATA_FMT_UNIT UINTPTRT_FMT_UNIT ":kevent";
+    static char *fmt = "O|hHI" DATA_FMT_UNIT UINTPTRT_FMT_UNIT ":kevent";
 
     EV_SET(&(self->e), 0, EVFILT_READ, EV_ADD, 0, 0, 0); /* defaults */