diff --git a/js/src/vm/Debugger.cpp b/js/src/vm/Debugger.cpp
index b7847ab5e9d5..8e429be38e03 100644
--- a/js/src/vm/Debugger.cpp
+++ b/js/src/vm/Debugger.cpp
@@ -4475,6 +4475,7 @@ Debugger::observesScript(JSScript *script) const
 Debugger::replaceFrameGuts(JSContext *cx, AbstractFramePtr from, AbstractFramePtr to,
                            ScriptFrameIter &iter)
 {
+    // Forward live Debugger.Frame objects.
     for (Debugger::FrameRange r(from); !r.empty(); r.popFront()) {
         RootedNativeObject frameobj(cx, r.frontFrame());
         Debugger *dbg = r.frontDebugger();
@@ -4497,6 +4498,9 @@ Debugger::replaceFrameGuts(JSContext *cx, AbstractFramePtr from, AbstractFramePt
         }
     }
 
+    // Rekey missingScopes to maintain Debugger.Environment identity.
+    DebugScopes::rekeyMissingScopes(cx, from, to);
+
     return true;
 }
 
diff --git a/js/src/vm/ScopeObject.cpp b/js/src/vm/ScopeObject.cpp
index 421deccf3345..7505cf798908 100644
--- a/js/src/vm/ScopeObject.cpp
+++ b/js/src/vm/ScopeObject.cpp
@@ -2380,6 +2380,22 @@ DebugScopes::hasLiveScope(ScopeObject &scope)
     return nullptr;
 }
 
+/* static */ void
+DebugScopes::rekeyMissingScopes(JSContext *cx, AbstractFramePtr from, AbstractFramePtr to)
+{
+    DebugScopes *scopes = cx->compartment()->debugScopes;
+    if (!scopes)
+        return;
+
+    for (MissingScopeMap::Enum e(scopes->missingScopes); !e.empty(); e.popFront()) {
+        ScopeIterKey key = e.front().key();
+        if (key.frame() == from) {
+            key.updateFrame(to);
+            e.rekeyFront(key);
+        }
+    }
+}
+
 /*****************************************************************************/
 
 static JSObject *
diff --git a/js/src/vm/ScopeObject.h b/js/src/vm/ScopeObject.h
index 8ba71c75e4f7..c73efb7a7af6 100644
--- a/js/src/vm/ScopeObject.h
+++ b/js/src/vm/ScopeObject.h
@@ -774,6 +774,7 @@ class ScopeIterKey
 
     void updateCur(JSObject *obj) { cur_ = obj; }
     void updateStaticScope(NestedScopeObject *obj) { staticScope_ = obj; }
+    void updateFrame(AbstractFramePtr frame) { frame_ = frame; }
 
     /* For use as hash policy */
     typedef ScopeIterKey Lookup;
@@ -941,6 +942,8 @@ class DebugScopes
     static bool updateLiveScopes(JSContext *cx);
     static ScopeIterVal *hasLiveScope(ScopeObject &scope);
 
+    static void rekeyMissingScopes(JSContext *cx, AbstractFramePtr from, AbstractFramePtr to);
+
     // In debug-mode, these must be called whenever exiting a scope that might
     // have stack-allocated locals.
     static void onPopCall(AbstractFramePtr frame, JSContext *cx);