Index: generic/nsf.c
===================================================================
diff -u -r27f3f462b1eab6ac548a8cf189317feede27278b -rbe661e5a99ad8b3a959ca10702d55e7ad1734fcb
--- generic/nsf.c	(.../nsf.c)	(revision 27f3f462b1eab6ac548a8cf189317feede27278b)
+++ generic/nsf.c	(.../nsf.c)	(revision be661e5a99ad8b3a959ca10702d55e7ad1734fcb)
@@ -31794,6 +31794,11 @@
             paramWrapperPtr->refCount);*/
 
     if (paramWrapperPtr->refCount <= 1) {
+      /*
+       * Sanity check: When refCount < 0, something is broken.
+       */
+      assert(paramWrapperPtr->refCount >= 0);
+
       ParamsFree(paramWrapperPtr->paramPtr);
       FREE(NsfParamWrapper, paramWrapperPtr);
     } else {