Index: generic/nsf.c
===================================================================
diff -u -rb70b7fe75a138e638fdff6d93b2ad63e9e6244a1 -r5bd8345b03b2cf99b4bf49372b0e3fcddeca3e10
--- generic/nsf.c	(.../nsf.c)	(revision b70b7fe75a138e638fdff6d93b2ad63e9e6244a1)
+++ generic/nsf.c	(.../nsf.c)	(revision 5bd8345b03b2cf99b4bf49372b0e3fcddeca3e10)
@@ -15780,7 +15780,7 @@
    } else if (firstChar == 's' && strncmp(option, "substdefaultoptions=", 20) == 0) {
 
      if ((paramPtr->flags & NSF_ARG_SUBST_DEFAULT) == 0u) {
-       return NsfPrintError(interp, "substdefaultoptions only allowes after substdefault'");
+       return NsfPrintError(interp, "substdefaultoptions only allowed after substdefault'");
 
      } else {
        int      result;