diff --git a/js/src/jit-test/tests/jaeger/recompile/bug645044.js b/js/src/jit-test/tests/jaeger/recompile/bug645044.js
new file mode 100644
index 00000000000..e31762a8e6a
--- /dev/null
+++ b/js/src/jit-test/tests/jaeger/recompile/bug645044.js
@@ -0,0 +1,4 @@
+
+this.__defineGetter__("x", gc);
+x.__proto__ = this;
+__proto__ = 44;
diff --git a/js/src/jsinfer.cpp b/js/src/jsinfer.cpp
index d86b2fa76e2..9b9f501a67d 100644
--- a/js/src/jsinfer.cpp
+++ b/js/src/jsinfer.cpp
@@ -839,13 +839,6 @@ PropertyAccess(JSContext *cx, JSScript *script, const jsbytecode *pc, TypeObject
 {
     JS_ASSERT_IF(!target, assign);
 
-    /* Reads from objects with unknown properties are unknown, writes to such objects are ignored. */
-    if (object->unknownProperties) {
-        if (!assign)
-            target->addType(cx, TYPE_UNKNOWN);
-        return;
-    }
-
     /* Monitor assigns on the 'prototype' property. */
     if (assign && id == id_prototype(cx)) {
         cx->compartment->types.monitorBytecode(cx, script, pc - script->code);
@@ -861,6 +854,13 @@ PropertyAccess(JSContext *cx, JSScript *script, const jsbytecode *pc, TypeObject
         return;
     }
 
+    /* Reads from objects with unknown properties are unknown, writes to such objects are ignored. */
+    if (object->unknownProperties) {
+        if (!assign)
+            target->addType(cx, TYPE_UNKNOWN);
+        return;
+    }
+
     /* Capture the effects of a standard property access. */
     if (target) {
         TypeSet *types = object->getProperty(cx, id, assign);