Index: generic/predefined.h
===================================================================
diff -u -rcd12f5a50d870605292d8c957cb2a079f1a17c10 -r782f6b060b16282799fe936bc528f512e562362a
--- generic/predefined.h	(.../predefined.h)	(revision cd12f5a50d870605292d8c957cb2a079f1a17c10)
+++ generic/predefined.h	(.../predefined.h)	(revision 782f6b060b16282799fe936bc528f512e562362a)
@@ -440,7 +440,6 @@
 "proc createBootstrapAttributeSlots {} {}\n"
 "::xotcl::Slot method type=hasmixin {name value arg} {\n"
 "if {![::xotcl::is $value hasmixin $arg]} {\n"
-"error \"Value '$value' of $name has not mixin $arg\"\n"
 "error \"expected object with mixin $arg but got \\\"$value\\\" for parameter $name\"}\n"
 "return $value}\n"
 "::xotcl::Slot method type=baseclass {name value} {\n"
Index: generic/predefined.xotcl
===================================================================
diff -u -rcd12f5a50d870605292d8c957cb2a079f1a17c10 -r782f6b060b16282799fe936bc528f512e562362a
--- generic/predefined.xotcl	(.../predefined.xotcl)	(revision cd12f5a50d870605292d8c957cb2a079f1a17c10)
+++ generic/predefined.xotcl	(.../predefined.xotcl)	(revision 782f6b060b16282799fe936bc528f512e562362a)
@@ -849,7 +849,6 @@
 
   ::xotcl::Slot method type=hasmixin {name value arg} {
     if {![::xotcl::is $value hasmixin $arg]} {
-      error "Value '$value' of $name has not mixin $arg"
       error "expected object with mixin $arg but got \"$value\" for parameter $name"
     }
     return $value
Index: generic/xotcl.c
===================================================================
diff -u -rc0b363cae9d43d3cb564b230233cc211470acd7e -r782f6b060b16282799fe936bc528f512e562362a
--- generic/xotcl.c	(.../xotcl.c)	(revision c0b363cae9d43d3cb564b230233cc211470acd7e)
+++ generic/xotcl.c	(.../xotcl.c)	(revision 782f6b060b16282799fe936bc528f512e562362a)
@@ -9650,7 +9650,7 @@
 }
 
 static int 
-ArgumentCheckHelper(Tcl_Interp *interp, Tcl_Obj *objPtr, struct XOTclParam CONST *pPtr,
+ArgumentCheckHelper(Tcl_Interp *interp, Tcl_Obj *objPtr, struct XOTclParam CONST *pPtr, int *flags,
                         ClientData *clientData, Tcl_Obj **outObjPtr) {
   int objc, i, result;
   Tcl_Obj **ov;
@@ -9678,6 +9678,7 @@
                      ObjStr(resultObj), (char *) NULL);
       DECR_REF_COUNT(resultObj);
       DECR_REF_COUNT(*outObjPtr);
+      *flags &= ~XOTCL_PC_MUST_DECR;
       break;
     }
   }
@@ -9717,7 +9718,7 @@
           /*fprintf(stderr, "switch to output list construction for value %s\n",
             ObjStr(elementObjPtr));*/
           *flags |= XOTCL_PC_MUST_DECR;
-          result = ArgumentCheckHelper(interp, objPtr, pPtr, clientData, outObjPtr);
+          result = ArgumentCheckHelper(interp, objPtr, pPtr, flags, clientData, outObjPtr);
           break;
         }
       } else {
Index: tests/parameters.xotcl
===================================================================
diff -u -rc0b363cae9d43d3cb564b230233cc211470acd7e -r782f6b060b16282799fe936bc528f512e562362a
--- tests/parameters.xotcl	(.../parameters.xotcl)	(revision c0b363cae9d43d3cb564b230233cc211470acd7e)
+++ tests/parameters.xotcl	(.../parameters.xotcl)	(revision 782f6b060b16282799fe936bc528f512e562362a)
@@ -558,7 +558,7 @@
 
 ? {d1 foo-hasmixin c1} "c1"
 ? {d1 foo-hasmixin o} \
-    "Value 'o' of x has not mixin ::M" \
+    {expected object with mixin ::M but got "o" for parameter x} \
     "does not have mixin M"
 
 ? {d1 foo-object o} "o"
@@ -693,7 +693,7 @@
 
 ? {ParamTest create p -mix c1} ::p
 ? {ParamTest create p -mix o} \
-    "Value 'o' of mix has not mixin M" \
+    {expected object with mixin M but got "o" for parameter mix} \
     "does not have mixin M"
 
 ? {ParamTest create p -u A} ::p
@@ -756,6 +756,22 @@
 C create c1
 ? {c1 foo {male female mann frau}} "m f m f"
 
+
+Object create tmpObj
+tmpObj method type=mType {name value arg:optional} {
+  if {[info exists arg]} {
+    puts stderr [arg=$arg]
+  }
+  puts stderr value=$value
+  if {$value} {
+    error invalid
+  }
+}
+
+? {::xotcl::valuecheck mType,slot=::tmpObj,multivalued {1 0}} 0 "fail on first value"
+? {::xotcl::valuecheck mType,slot=::tmpObj,multivalued {0 0 0}} 1 "all pass"
+? {::xotcl::valuecheck mType,slot=::tmpObj,multivalued {0 1}} 0 "fail o last value"
+
 #######################################################
 # slot specific converter
 #######################################################