diff --git a/js/src/devtools/rootAnalysis/analyzeRoots.js b/js/src/devtools/rootAnalysis/analyzeRoots.js
index a10f63d0cadd..a0fa94e061c2 100644
--- a/js/src/devtools/rootAnalysis/analyzeRoots.js
+++ b/js/src/devtools/rootAnalysis/analyzeRoots.js
@@ -29,7 +29,7 @@ var batch = (scriptArgs[5]|0) || 1;
 var numBatches = (scriptArgs[6]|0) || 1;
 var tmpfile = scriptArgs[7] || "tmp.txt";
 
-GCSuppressionTypes = loadTypeInfo(typeInfoFile)["Suppress GC"];
+GCSuppressionTypes = loadTypeInfo(typeInfoFile)["Suppress GC"] || [];
 
 var gcFunctions = {};
 var text = snarf("gcFunctions.lst").split("\n");
diff --git a/js/src/devtools/rootAnalysis/computeCallgraph.js b/js/src/devtools/rootAnalysis/computeCallgraph.js
index ae30d9bd5bca..dab3f76216f6 100644
--- a/js/src/devtools/rootAnalysis/computeCallgraph.js
+++ b/js/src/devtools/rootAnalysis/computeCallgraph.js
@@ -308,7 +308,7 @@ function processBody(functionName, body)
     }
 }
 
-GCSuppressionTypes = loadTypeInfo(typeInfo_filename)["Suppress GC"];
+GCSuppressionTypes = loadTypeInfo(typeInfo_filename)["Suppress GC"] || [];
 
 var xdb = xdbLibrary();
 xdb.open("src_comp.xdb");
diff --git a/js/src/devtools/rootAnalysis/run-test.py b/js/src/devtools/rootAnalysis/run-test.py
index 113e5fe351a1..3bc9085a0aaf 100644
--- a/js/src/devtools/rootAnalysis/run-test.py
+++ b/js/src/devtools/rootAnalysis/run-test.py
@@ -40,7 +40,7 @@ parser.add_argument(
     '--verbose', '-v', action='store_true',
     help='Display verbose output, including commands executed')
 parser.add_argument(
-    'tests', nargs='*', default=['sixgill-tree', 'suppression', 'hazards'],
+    'tests', nargs='*', default=['sixgill-tree', 'suppression', 'hazards', 'exceptions'],
     help='tests to run')
 
 cfg = parser.parse_args()
diff --git a/js/src/devtools/rootAnalysis/t/exceptions/source.cpp b/js/src/devtools/rootAnalysis/t/exceptions/source.cpp
new file mode 100644
index 000000000000..14169740e8f8
--- /dev/null
+++ b/js/src/devtools/rootAnalysis/t/exceptions/source.cpp
@@ -0,0 +1,42 @@
+#define ANNOTATE(property) __attribute__((tag(property)))
+
+struct Cell { int f; } ANNOTATE("GC Thing");
+
+extern void GC() ANNOTATE("GC Call");
+
+void GC()
+{
+    // If the implementation is too trivial, the function body won't be emitted at all.
+    asm("");
+}
+
+class RAII_GC {
+  public:
+    RAII_GC() {}
+    ~RAII_GC() { GC(); }
+};
+
+// ~AutoSomething calls GC because of the RAII_GC field. The constructor,
+// though, should *not* GC -- unless it throws an exception. Which is not
+// possible when compiled with -fno-exceptions.
+class AutoSomething {
+    RAII_GC gc;
+  public:
+    AutoSomething() : gc() {
+        asm(""); // Ooh, scary, this might throw an exception
+    }
+    ~AutoSomething() {
+        asm("");
+    }
+};
+
+extern void usevar(Cell* cell);
+
+void f() {
+    Cell* thing = nullptr; // Live range starts here
+
+    {
+        AutoSomething smth; // Constructor can GC only if exceptions are enabled
+        usevar(thing); // Live range ends here
+    } // In particular, 'thing' is dead at the destructor, so no hazard
+}
diff --git a/js/src/devtools/rootAnalysis/t/exceptions/test.py b/js/src/devtools/rootAnalysis/t/exceptions/test.py
new file mode 100644
index 000000000000..f6d7f5e353f2
--- /dev/null
+++ b/js/src/devtools/rootAnalysis/t/exceptions/test.py
@@ -0,0 +1,19 @@
+test.compile("source.cpp", '-fno-exceptions')
+test.run_analysis_script('gcTypes')
+
+hazards = test.load_hazards()
+assert(len(hazards) == 0)
+
+# If we compile with exceptions, then there *should* be a hazard because
+# AutoSomething::AutoSomething might throw an exception, which would cause the
+# partially-constructed value to be torn down, which will call ~RAII_GC.
+
+test.compile("source.cpp", '-fexceptions')
+test.run_analysis_script('gcTypes')
+
+hazards = test.load_hazards()
+assert(len(hazards) == 1)
+hazard = hazards[0]
+assert(hazard.function == 'void f()')
+assert(hazard.variable == 'thing')
+assert("AutoSomething::AutoSomething" in hazard.GCFunction)
diff --git a/js/src/devtools/rootAnalysis/t/testlib.py b/js/src/devtools/rootAnalysis/t/testlib.py
index 6f48ab19f278..438398f1ed66 100644
--- a/js/src/devtools/rootAnalysis/t/testlib.py
+++ b/js/src/devtools/rootAnalysis/t/testlib.py
@@ -31,10 +31,11 @@ class Test(object):
     def binpath(self, prog):
         return os.path.join(self.cfg.sixgill_bin, prog)
 
-    def compile(self, source):
-        cmd = "{CXX} -c {source} -O3 -std=c++11 -fplugin={sixgill} -fplugin-arg-xgill-mangle=1".format(
+    def compile(self, source, options = ''):
+        cmd = "{CXX} -c {source} -O3 -std=c++11 -fplugin={sixgill} -fplugin-arg-xgill-mangle=1 {options}".format(
             source=self.infile(source),
-            CXX=self.cfg.cxx, sixgill=self.cfg.sixgill_plugin)
+            CXX=self.cfg.cxx, sixgill=self.cfg.sixgill_plugin,
+            options=options)
         if self.cfg.verbose:
             print("Running %s" % cmd)
         subprocess.check_call(["sh", "-c", cmd])
@@ -75,7 +76,7 @@ sixgill_bin = '{bindir}'
         self.run_analysis_script("gcTypes", upto="gcTypes")
 
     def computeHazards(self):
-        self.run_analysis_script("callgraph")
+        self.run_analysis_script("gcTypes")
 
     def load_text_file(self, filename, extract=lambda l: l):
         fullpath = os.path.join(self.outdir, filename)