diff --git a/js/src/devtools/rootAnalysis/annotations.js b/js/src/devtools/rootAnalysis/annotations.js
index e1de86219a0..a99d437babd 100644
--- a/js/src/devtools/rootAnalysis/annotations.js
+++ b/js/src/devtools/rootAnalysis/annotations.js
@@ -63,6 +63,7 @@ var ignoreCallees = {
     "js::ion::MDefinition.opName" : true, // macro generated virtuals just return a constant
     "js::ion::LInstruction.getDef" : true, // virtual but no implementation can GC
     "js::ion::IonCache.kind" : true, // macro generated virtuals just return a constant
+    "icu_50::UObject.__deleting_dtor" : true, // destructors in ICU code can't cause GC
 };
 
 function fieldCallCannotGC(csu, fullfield)
@@ -133,7 +134,8 @@ function isRootedTypeName(name)
 {
     if (name == "mozilla::ErrorResult" ||
         name == "js::frontend::TokenStream" ||
-        name == "js::frontend::TokenStream::Position")
+        name == "js::frontend::TokenStream::Position" ||
+        name == "ModuleCompiler")
     {
         return true;
     }
diff --git a/js/src/frontend/TokenStream.h b/js/src/frontend/TokenStream.h
index 8c1503a2081..3c5e2f7a85c 100644
--- a/js/src/frontend/TokenStream.h
+++ b/js/src/frontend/TokenStream.h
@@ -436,7 +436,7 @@ class StrictModeGetter {
 //
 // The methods seek() and tell() allow to rescan from a previous visited
 // location of the buffer.
-class TokenStream
+class MOZ_STACK_CLASS TokenStream
 {
     /* Unicode separators that are treated as line terminators, in addition to \n, \r */
     enum {
diff --git a/js/src/ion/AsmJS.cpp b/js/src/ion/AsmJS.cpp
index bcfc585359d..4a9b863775e 100644
--- a/js/src/ion/AsmJS.cpp
+++ b/js/src/ion/AsmJS.cpp
@@ -894,7 +894,16 @@ typedef Vector<MBasicBlock*,16> CaseVector;
 // to add a new exit or reuse an existing one. The key is an ExitDescriptor
 // (which holds the exit pairing) and the value is an index into the
 // Vector<Exit> stored in the AsmJSModule.
-class ModuleCompiler
+//
+// Rooting note: ModuleCompiler is a stack class that contains unrooted
+// PropertyName (JSAtom) pointers.  This is safe because it cannot be
+// constructed without a TokenStream reference.  TokenStream is itself a stack
+// class that cannot be constructed without an AutoKeepAtoms being live on the
+// stack, which prevents collection of atoms.
+//
+// ModuleCompiler is marked as rooted in the rooting analysis.  Don't add
+// non-JSAtom pointers, or this will break!
+class MOZ_STACK_CLASS ModuleCompiler
 {
   public:
     class Func