diff --git a/js/src/jsinterp.cpp b/js/src/jsinterp.cpp
index 2ab8b859358..fb2c1a5b856 100644
--- a/js/src/jsinterp.cpp
+++ b/js/src/jsinterp.cpp
@@ -4198,7 +4198,7 @@ BEGIN_CASE(JSOP_CALLPROP)
         }
     }
 #if JS_HAS_NO_SUCH_METHOD
-    if (JS_UNLIKELY(rval.isUndefined()) && regs.sp[-1].isObject()) {
+    if (JS_UNLIKELY(rval.isPrimitive()) && regs.sp[-1].isObject()) {
         LOAD_ATOM(0, atom);
         regs.sp[-2].setString(atom);
         if (!js_OnUnknownMethod(cx, regs.sp - 2))
@@ -4458,7 +4458,7 @@ BEGIN_CASE(JSOP_CALLELEM)
         goto error;
 
 #if JS_HAS_NO_SUCH_METHOD
-    if (JS_UNLIKELY(regs.sp[-2].isUndefined()) && thisv.isObject()) {
+    if (JS_UNLIKELY(regs.sp[-2].isPrimitive()) && thisv.isObject()) {
         /* For js_OnUnknownMethod, sp[-2] is the index, and sp[-1] is the object missing it. */
         regs.sp[-2] = regs.sp[-1];
         regs.sp[-1].setObject(*thisObj);
diff --git a/js/src/methodjit/PolyIC.cpp b/js/src/methodjit/PolyIC.cpp
index 5f003b3b257..4dc89e59631 100644
--- a/js/src/methodjit/PolyIC.cpp
+++ b/js/src/methodjit/PolyIC.cpp
@@ -1850,7 +1850,7 @@ ic::CallProp(VMFrame &f, ic::PICInfo *pic)
     }
 
 #if JS_HAS_NO_SUCH_METHOD
-    if (JS_UNLIKELY(rval.isUndefined()) && regs.sp[-1].isObject()) {
+    if (JS_UNLIKELY(rval.isPrimitive()) && regs.sp[-1].isObject()) {
         regs.sp[-2].setString(pic->atom);
         if (!js_OnUnknownMethod(cx, regs.sp - 2))
             THROW();
@@ -2369,7 +2369,7 @@ ic::CallElement(VMFrame &f, ic::GetElementIC *ic)
         THROW();
 
 #if JS_HAS_NO_SUCH_METHOD
-    if (JS_UNLIKELY(f.regs.sp[-2].isUndefined()) && thisv.isObject()) {
+    if (JS_UNLIKELY(f.regs.sp[-2].isPrimitive()) && thisv.isObject()) {
         f.regs.sp[-2] = f.regs.sp[-1];
         f.regs.sp[-1].setObject(*thisObj);
         if (!js_OnUnknownMethod(cx, f.regs.sp - 2))
diff --git a/js/src/methodjit/StubCalls.cpp b/js/src/methodjit/StubCalls.cpp
index 0b88920369c..c6ce8724649 100644
--- a/js/src/methodjit/StubCalls.cpp
+++ b/js/src/methodjit/StubCalls.cpp
@@ -514,7 +514,7 @@ stubs::CallElem(VMFrame &f)
         THROW();
 
 #if JS_HAS_NO_SUCH_METHOD
-    if (JS_UNLIKELY(regs.sp[-2].isUndefined()) && thisv.isObject()) {
+    if (JS_UNLIKELY(regs.sp[-2].isPrimitive()) && thisv.isObject()) {
         regs.sp[-2] = regs.sp[-1];
         regs.sp[-1].setObject(*thisObj);
         if (!js_OnUnknownMethod(cx, regs.sp - 2))
@@ -1994,7 +1994,7 @@ stubs::CallProp(VMFrame &f, JSAtom *origAtom)
         }
     }
 #if JS_HAS_NO_SUCH_METHOD
-    if (JS_UNLIKELY(rval.isUndefined()) && regs.sp[-1].isObject()) {
+    if (JS_UNLIKELY(rval.isPrimitive()) && regs.sp[-1].isObject()) {
         regs.sp[-2].setString(origAtom);
         if (!js_OnUnknownMethod(cx, regs.sp - 2))
             THROW();
diff --git a/js/src/tests/js1_5/extensions/jstests.list b/js/src/tests/js1_5/extensions/jstests.list
index 3816c033c53..1953e18cf6c 100644
--- a/js/src/tests/js1_5/extensions/jstests.list
+++ b/js/src/tests/js1_5/extensions/jstests.list
@@ -223,3 +223,4 @@ script scope-001.js
 fails-if(Android) script toLocaleFormat-01.js
 fails-if(xulRuntime.OS=="WINNT") script toLocaleFormat-02.js
 script regress-543839.js
+script regress-564577.js
diff --git a/js/src/tests/js1_5/extensions/regress-564577.js b/js/src/tests/js1_5/extensions/regress-564577.js
new file mode 100644
index 00000000000..64edacdfec6
--- /dev/null
+++ b/js/src/tests/js1_5/extensions/regress-564577.js
@@ -0,0 +1,79 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ * Contributor: Matthew Draper <matthew@trebex.net>
+ */
+
+var gTestfile = 'regress-564577.js';
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 564577;
+var summary = '__noSuchMethod__ when property exists';
+var actual = '';
+var expect = '';
+
+
+//-----------------------------------------------------------------------------
+test();
+//-----------------------------------------------------------------------------
+
+function test()
+{
+  enterFunc ('test');
+  printBugNumber(BUGNUMBER);
+  printStatus (summary);
+
+ 
+  var o = {
+    aaa: undefined,
+    bbb: null,
+    ccc: 77,
+    ddd: 'foo',
+    eee: {},
+    fff: /./,
+    __noSuchMethod__: function (id, args)
+    {
+      return(id + '('+args.join(',')+') ' + this[id]);
+    }
+  };
+
+  status = summary + ' ' + inSection(1) + ' ';
+  actual = o.aaa();
+  expect = 'aaa() undefined';
+  reportCompare(expect, actual, status);
+
+  status = summary + ' ' + inSection(2) + ' ';
+  actual = o.bbb();
+  expect = 'bbb() null';
+  reportCompare(expect, actual, status);
+
+  status = summary + ' ' + inSection(3) + ' ';
+  actual = o.ccc();
+  expect = 'ccc() 77';
+  reportCompare(expect, actual, status);
+
+  status = summary + ' ' + inSection(4) + ' ';
+  actual = o.ddd();
+  expect = 'ddd() foo';
+  reportCompare(expect, actual, status);
+
+  status = summary + ' ' + inSection(5) + ' ';
+  try {
+    actual = o.eee();
+  } catch(e) {
+    actual = e + '';
+  }
+  expect = 'TypeError: o.eee is not a function';
+  reportCompare(expect, actual, status);
+
+  status = summary + ' ' + inSection(6) + ' ';
+  try {
+    actual = o.fff('xyz') + '';
+  } catch(e) {
+    actual = e + '';
+  }
+  expect = 'TypeError: o.fff is not a function';
+  reportCompare(expect, actual, status);
+
+  exitFunc('test');
+}