Issue #14173: Avoid crashing when reading a signal handler during interpreter shutdown.
diff --git a/Misc/NEWS b/Misc/NEWS
index 6a3f17c..da68f26 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -47,6 +47,9 @@
 Library
 -------
 
+- Issue #14173: Avoid crashing when reading a signal handler during
+  interpreter shutdown.
+
 - Issue #16316: mimetypes now recognizes the .xz and .txz (.tar.xz) extensions.
 
 - Issue #15902: Fix imp.load_module() accepting None as a file when loading an
diff --git a/Modules/signalmodule.c b/Modules/signalmodule.c
index 0cc7237..fbe1bb7 100644
--- a/Modules/signalmodule.c
+++ b/Modules/signalmodule.c
@@ -344,7 +344,10 @@
     Handlers[sig_num].tripped = 0;
     Py_INCREF(obj);
     Handlers[sig_num].func = obj;
-    return old_handler;
+    if (old_handler != NULL)
+        return old_handler;
+    else
+        Py_RETURN_NONE;
 }
 
 PyDoc_STRVAR(signal_doc,
@@ -372,8 +375,13 @@
         return NULL;
     }
     old_handler = Handlers[sig_num].func;
-    Py_INCREF(old_handler);
-    return old_handler;
+    if (old_handler != NULL) {
+        Py_INCREF(old_handler);
+        return old_handler;
+    }
+    else {
+        Py_RETURN_NONE;
+    }
 }
 
 PyDoc_STRVAR(getsignal_doc,