diff --git a/js/src/jsfriendapi.h b/js/src/jsfriendapi.h
index b8d2de3f490..9bdb8083309 100644
--- a/js/src/jsfriendapi.h
+++ b/js/src/jsfriendapi.h
@@ -593,7 +593,8 @@ SizeOfJSContext();
     D(DOM_WORKER)                               \
     D(INTER_SLICE_GC)                           \
     D(REFRESH_FRAME)                            \
-    D(FULL_GC_TIMER)
+    D(FULL_GC_TIMER)                            \
+    D(SHUTDOWN_CC)
 
 namespace gcreason {
 
diff --git a/js/src/jsgc.cpp b/js/src/jsgc.cpp
index 43134e65f5a..331c64a8775 100644
--- a/js/src/jsgc.cpp
+++ b/js/src/jsgc.cpp
@@ -3799,13 +3799,15 @@ static bool
 ShouldCleanUpEverything(JSRuntime *rt, gcreason::Reason reason)
 {
     // During shutdown, we must clean everything up, for the sake of leak
-    // detection. When a runtime has no contexts, or we're doing a forced GC,
-    // those are strong indications that we're shutting down.
+    // detection. When a runtime has no contexts, or we're doing a GC before a
+    // shutdown CC, those are strong indications that we're shutting down.
     //
     // DEBUG_MODE_GC indicates we're discarding code because the debug mode
     // has changed; debug mode affects the results of bytecode analysis, so
     // we need to clear everything away.
-    return !rt->hasContexts() || reason == gcreason::CC_FORCED || reason == gcreason::DEBUG_MODE_GC;
+    return !rt->hasContexts() ||
+           reason == gcreason::SHUTDOWN_CC ||
+           reason == gcreason::DEBUG_MODE_GC;
 }
 
 static void
@@ -3824,7 +3826,7 @@ Collect(JSRuntime *rt, bool incremental, int64_t budget,
 #ifdef JS_GC_ZEAL
     bool restartVerify = rt->gcVerifyData &&
                          rt->gcZeal() == ZealVerifierValue &&
-                         reason != gcreason::CC_FORCED &&
+                         reason != gcreason::SHUTDOWN_CC &&
                          rt->hasContexts();
 
     struct AutoVerifyBarriers {
diff --git a/xpcom/base/nsCycleCollector.cpp b/xpcom/base/nsCycleCollector.cpp
index f992eaec948..d08503bcbfc 100644
--- a/xpcom/base/nsCycleCollector.cpp
+++ b/xpcom/base/nsCycleCollector.cpp
@@ -2605,7 +2605,7 @@ nsCycleCollector::GCIfNeeded(bool aForceGC)
     // mJSRuntime->Collect() must be called from the main thread,
     // because it invokes XPCJSRuntime::GCCallback(cx, JSGC_BEGIN)
     // which returns false if not in the main thread.
-    mJSRuntime->Collect(js::gcreason::CC_FORCED, nsGCNormal);
+    mJSRuntime->Collect(aForceGC ? js::gcreason::SHUTDOWN_CC : js::gcreason::CC_FORCED, nsGCNormal);
     timeLog.Checkpoint("GC()");
 }