diff --git a/src/integrators/photonmapper/photonmapper.cpp b/src/integrators/photonmapper/photonmapper.cpp
index d77c7fbc..d45a323d 100644
--- a/src/integrators/photonmapper/photonmapper.cpp
+++ b/src/integrators/photonmapper/photonmapper.cpp
@@ -87,7 +87,8 @@ MTS_NAMESPACE_BEGIN
  */
 class PhotonMapIntegrator : public SamplingIntegrator {
 public:
-	PhotonMapIntegrator(const Properties &props) : SamplingIntegrator(props) {
+	PhotonMapIntegrator(const Properties &props) : SamplingIntegrator(props),
+		  m_parentIntegrator(NULL) {
 		/* Number of lsamples for direct illumination */
 		m_directSamples = props.getInteger("directSamples", 16);
 		/* Number of BSDF samples when intersecting a glossy material */
@@ -150,7 +151,7 @@ public:
 
 	/// Unserialize from a binary data stream
 	PhotonMapIntegrator(Stream *stream, InstanceManager *manager)
-	 : SamplingIntegrator(stream, manager) {
+	 : SamplingIntegrator(stream, manager), m_parentIntegrator(NULL) {
 		m_directSamples = stream->readInt();
 		m_glossySamples = stream->readInt();
 		m_maxDepth = stream->readInt();
diff --git a/src/subsurface/irrproc.cpp b/src/subsurface/irrproc.cpp
index b5ff2cde..b546fb0e 100644
--- a/src/subsurface/irrproc.cpp
+++ b/src/subsurface/irrproc.cpp
@@ -55,6 +55,7 @@ public:
 		m_sampler = static_cast<Sampler *>(getResource("sampler"));
 		m_integrator = static_cast<SamplingIntegrator *>(getResource("integrator"));
 		m_scene->wakeup(NULL, m_resources);
+		m_integrator->wakeup(NULL, m_resources);
 	}
 
 	void process(const WorkUnit *workUnit, WorkResult *workResult,