new file mode 100644
--- /dev/null
+++ b/js/src/jit-test/tests/realms/bug1487238.js
@@ -0,0 +1,3 @@
+// |jit-test| error: TypeError
+var x = newGlobal({sameCompartmentAs: this});
+x instanceof x.Map.prototype.set;

--- a/js/src/vm/BytecodeUtil.cpp
+++ b/js/src/vm/BytecodeUtil.cpp
@@ -2257,17 +2257,17 @@ DecompileExpressionFromStack(JSContext* 
     return true;
 #endif
 
     if (spindex == JSDVG_IGNORE_STACK)
         return true;
 
     FrameIter frameIter(cx);
 
-    if (frameIter.done() || !frameIter.hasScript() || frameIter.compartment() != cx->compartment())
+    if (frameIter.done() || !frameIter.hasScript() || frameIter.realm() != cx->realm())
         return true;
 
     /*
      * FIXME: Fall back if iter.isIon(), since the stack snapshot may be for the
      * previous pc (see bug 831120).
      */
     if (frameIter.isIon())
         return true;
@@ -2347,17 +2347,17 @@ DecompileArgumentFromStack(JSContext* cx
     /*
      * Get the second-to-top frame, the non-self-hosted caller of the builtin
      * that called the intrinsic.
      */
     ++frameIter;
     if (frameIter.done() ||
         !frameIter.hasScript() ||
         frameIter.script()->selfHosted() ||
-        frameIter.compartment() != cx->compartment())
+        frameIter.realm() != cx->realm())
     {
         return true;
     }
 
     RootedScript script(cx, frameIter.script());
     jsbytecode* current = frameIter.pc();
 
     MOZ_ASSERT(script->containsPC(current));