Index: generic/nsf.c
===================================================================
diff -u -N -r5425e020380d24f7e9d082ddc030478b93e894d2 -r33d063a3296efd044652cba8668e25cef4797b66
--- generic/nsf.c	(.../nsf.c)	(revision 5425e020380d24f7e9d082ddc030478b93e894d2)
+++ generic/nsf.c	(.../nsf.c)	(revision 33d063a3296efd044652cba8668e25cef4797b66)
@@ -26351,7 +26351,7 @@
   length = strlen(methodName);
 
   for (j = 0; j < length; j++) {
-    if (methodName[j] == ':' || methodName[j] == ' ') {
+    if (methodName[j] == ':' || NsfHasTclSpace(&methodName[j])) {
       break;
     }
   }
Index: tests/parameters.test
===================================================================
diff -u -N -r5425e020380d24f7e9d082ddc030478b93e894d2 -r33d063a3296efd044652cba8668e25cef4797b66
--- tests/parameters.test	(.../parameters.test)	(revision 5425e020380d24f7e9d082ddc030478b93e894d2)
+++ tests/parameters.test	(.../parameters.test)	(revision 33d063a3296efd044652cba8668e25cef4797b66)
@@ -1345,6 +1345,7 @@
   ? {o ints hugo} {invalid value in "hugo": expected integer but got "hugo" for parameter "ints"}
   ? {o o o} o
   ? {::nsf::method::setter o {d default}} {parameter "d" is not allowed to have default "default"}
+  ? {::nsf::method::setter o "d\ndefault"} {parameter "d" is not allowed to have default "default"}
   ? {::nsf::method::setter o -x} {invalid setter name "-x" (must not start with a dash or colon)}
 }