--- a/js/src/asmjs/WasmFrameIterator.cpp
+++ b/js/src/asmjs/WasmFrameIterator.cpp
@@ -510,16 +510,17 @@ ProfilingFrameIterator::initFromFP(const
 typedef JS::ProfilingFrameIterator::RegisterState RegisterState;
 
 ProfilingFrameIterator::ProfilingFrameIterator(const WasmActivation& activation,
                                                const RegisterState& state)
   : module_(&activation.module()),
     codeRange_(nullptr),
     callerFP_(nullptr),
     callerPC_(nullptr),
+    stackAddress_(nullptr),
     exitReason_(ExitReason::None)
 {
     // If profiling hasn't been enabled for this module, then CallerFPFromFP
     // will be trash, so ignore the entire activation. In practice, this only
     // happens if profiling is enabled while module->active() (in this case,
     // profiling will be enabled when the module becomes inactive and gets
     // called again).
     if (!module_->profilingEnabled()) {