Index: generic/nsf.c
===================================================================
diff -u -r79bca8ba3bc60bdb2bacd88af12a24cad002f409 -r918dad9936cd257821e13fa823ff94e89c3c9ea5
--- generic/nsf.c	(.../nsf.c)	(revision 79bca8ba3bc60bdb2bacd88af12a24cad002f409)
+++ generic/nsf.c	(.../nsf.c)	(revision 918dad9936cd257821e13fa823ff94e89c3c9ea5)
@@ -16987,10 +16987,23 @@
     ov[3] = AddPrefixToBody(body, 0, &parsedParam);
   }
 
+  /*
+   * Check, if the cmd exists already in the namespace. If so, delete it from
+   * there.
+   */
+  {
+    Tcl_HashEntry *hPtr = Tcl_FindHashEntry(Tcl_Namespace_cmdTablePtr(nsPtr), methodName);
+    if (hPtr != NULL) {
+      NSDeleteCmd(interp, nsPtr, methodName);
+      //fprintf(stderr, "... DELETE preexisting cmd %s in ns %s\n", methodName, nsPtr->fullName);
+    }
+  }
+
   //Tcl_PushCallFrame(interp, (Tcl_CallFrame *)framePtr, nsPtr, 0);
   /*
    * Create the method in the provided namespace.
    */
+
   result = Tcl_ProcObjCmd(NULL, interp, 4, ov);
 
   if (likely(result == TCL_OK)) {
Index: tests/alias.test
===================================================================
diff -u -r275da34d3d7a874a451eced58242b738c8a37d1a -r918dad9936cd257821e13fa823ff94e89c3c9ea5
--- tests/alias.test	(.../alias.test)	(revision 275da34d3d7a874a451eced58242b738c8a37d1a)
+++ tests/alias.test	(.../alias.test)	(revision 918dad9936cd257821e13fa823ff94e89c3c9ea5)
@@ -377,7 +377,7 @@
 ::nsf::method::alias ::C BAR ::foo  
 
 # AliasDelete in AddObjectMethod
-? {info exists ::nsf::alias(::o,BAR,1)} 1
+? {info exists ::nsf::alias(::o,BAR,1)} 1 "delete alias via redefinition of a method"
 ::o public object method BAR {} {;}
 ? {info exists ::nsf::alias(::o,BAR,1)} 0