Index: generic/nsf.c
===================================================================
diff -u -N -r33d063a3296efd044652cba8668e25cef4797b66 -r462bf8f1d53c0f2bcaa795f542e2f65cdab996b5
--- generic/nsf.c	(.../nsf.c)	(revision 33d063a3296efd044652cba8668e25cef4797b66)
+++ generic/nsf.c	(.../nsf.c)	(revision 462bf8f1d53c0f2bcaa795f542e2f65cdab996b5)
@@ -3925,7 +3925,7 @@
   nonnull_assert(methodObj != NULL);
   nonnull_assert(pcl != NULL);
 
-  if (strchr(ObjStr(methodObj), ' ') != NULL) {
+  if (NsfHasTclSpace(ObjStr(methodObj))) {
     lookupFunction = SearchComplexCMethod;
   } else {
     lookupFunction = SearchSimpleCMethod;
Index: tests/nsf-cmd.test
===================================================================
diff -u -N -r67401de3f9bcd5d59c54133756398953d369fcca -r462bf8f1d53c0f2bcaa795f542e2f65cdab996b5
--- tests/nsf-cmd.test	(.../nsf-cmd.test)	(revision 67401de3f9bcd5d59c54133756398953d369fcca)
+++ tests/nsf-cmd.test	(.../nsf-cmd.test)	(revision 462bf8f1d53c0f2bcaa795f542e2f65cdab996b5)
@@ -53,6 +53,11 @@
   ? {nsf::cmd::info submethods $::handle} ""
   ? {nsf::cmd::info returns $::handle} ""
 
+  # alternative string reps for pattern list
+  foreach char {\t \n \r \f \v} {
+    ? [list p1 info lookup method "string${char}match"] [join [list {*}$::handle] $char]
+  }
+
   #
   # An C-defined method inherited from nx::Object
   #